Network troubleshooting technician providing live chat help

Joe B.

Reviewed for technical accuracy

Specialities: Home & office Wi-Fi, VPN clients (AnyConnect, GlobalProtect, OpenVPN), Windows/macOS network issues, DNS & IP configuration, remote work setup

Fix Wi-Fi drops when VPN connects — internet disconnects when VPN is on, company VPN not working on Wi-Fi

Technician avatar Technician
Hi! We’ll sort out why your Wi-Fi drops when VPN connects so you can work securely without losing internet. I just need a quick picture of what’s happening.

When you’re not on VPN, does Wi-Fi work normally for browsing and video calls? As soon as you click “connect” in the VPN client, do you see Wi-Fi disconnect, the network icon turn into a globe, or do apps just say “no internet”?

Also, is this your company VPN (Cisco AnyConnect, GlobalProtect, FortiClient, Pulse Secure, etc.) or a personal VPN like NordVPN/ExpressVPN? And does the VPN work on other connections such as a mobile hotspot or office Wi-Fi, or does it only fail on this one home Wi-Fi network?
Customer
Yeah, without VPN everything on Wi-Fi is perfect — streaming, Teams, web browsing. The problem is only when I connect to our company VPN (Cisco AnyConnect). I click Connect, it says “Establishing VPN…” and then my Wi-Fi instantly disconnects. Windows shows the globe icon and all Wi-Fi networks disappear for a few seconds.

If I tether my laptop to my phone’s hotspot, VPN works fine. It also works if I plug the laptop into the router with an Ethernet cable. It seems like VPN only kills Wi-Fi when I’m on my home wireless network.
Technician avatar Technician
That’s really helpful. Since VPN works on hotspot and Ethernet, your company server and account are fine. The issue is the interaction between:

• Your Wi-Fi adapter / driver
• The VPN virtual adapter (AnyConnect)
• And sometimes the home router’s firewall

On Windows, when Wi-Fi disconnects whenever VPN connects, it’s usually one of these:
• A buggy Wi-Fi driver that crashes when the VPN creates a secure tunnel.
• VPN is set to force all traffic through the tunnel, and your router blocks IPSec / SSL VPN traffic, so Windows marks the connection as “no internet”.
• A strict VPN kill switch / “block non-VPN traffic” option that cuts Wi-Fi if the tunnel isn’t fully up.
• Wrong MTU size or IPv6 conflict causing packets to fail once the VPN is active.

We’ll go layer by layer: first confirm basic Wi-Fi stability, then fix Windows 11 network settings, then tune your VPN protocol and, if needed, tweak the router so Wi-Fi stays up while VPN is connected.
Customer
That makes sense. For what it’s worth, my phone and my partner’s laptop can stay on Wi-Fi fine while I’m fighting with VPN on this laptop. Only my work laptop has the issue where Wi-Fi disconnects when VPN connects.

I’m on Windows 11, using the official Cisco AnyConnect from our IT department. They just told me, “If it works on hotspot it’s your home internet,” but the home Wi-Fi itself is solid for everything else.
Technician avatar Technician
Perfect, so we’ll start on the laptop side. The goal is to stop the Wi-Fi adapter from crashing when VPN starts.

Step A — Refresh Wi-Fi driver and network stack (Windows 11)
1) In Device Manager → Network adapters, right-click your Wi-Fi adapter (Intel/Realtek/Qualcomm) → Update driver → “Search automatically”. If your laptop maker has a newer driver on their site, use that instead.
2) Still on the Wi-Fi adapter’s properties, open the Power Management tab and uncheck “Allow the computer to turn off this device to save power”. Power saving plus VPN often equals random Wi-Fi dropping when VPN connects.
3) Open Settings → Network & internet → Advanced network settings and use the option to Reset network. This rebuilds all network adapters (Wi-Fi + VPN virtual adapters) in one go.
4) Reboot the laptop, connect to your home Wi-Fi, confirm normal internet, and then try connecting to the VPN again.

Let me know if the behaviour changed — does Wi-Fi still cut out the moment the VPN starts, or does it stay connected but you lose access to websites?
Customer
I updated the Wi-Fi driver and disabled the power-saving option. The network reset took a while but it’s done now. After the reboot, I re-joined my Wi-Fi and tested.

Now when I click Connect in AnyConnect, the Wi-Fi doesn’t completely disappear anymore, but Windows switches to the globe icon saying “No internet, secured” as soon as the VPN finishes connecting. Teams disconnects and I can’t browse anything, even internal company sites.
Technician avatar Technician
Good, that confirms the Wi-Fi driver crash is largely fixed. Now it’s a routing / VPN policy issue — Windows thinks there’s no internet with VPN on.

Step B — Tweak VPN client & IP settings
1) In the AnyConnect window, click the gear / settings icon if available. Look for options like:
• “Block connections to untrusted servers”
• “Disable local LAN access”
• “Always on VPN” or “VPN kill switch / block non-VPN traffic”
Temporarily untick anything that sounds like “block local or non-VPN traffic” and reconnect.

2) On your Wi-Fi adapter properties (Control Panel → Network & Internet → Network Connections → Wi-Fi → Properties):
• Uncheck Internet Protocol Version 6 (TCP/IPv6) if your company doesn’t require it. Some corporate VPNs break when IPv6 is active on home routers.
• Leave IPv4 on “Obtain an IP address automatically” and “Obtain DNS server automatically” unless IT told you otherwise.

3) Try connecting VPN again. If it still flips to “No internet, secured”, we’ll test a different VPN protocol/transport (for example switching between UDP/TCP, or from IPSec to SSL if your profile allows that), which often stabilizes Wi-Fi when the original protocol is blocked or mangled by the router.
Customer
In AnyConnect there was an option enabled called “Block connections to untrusted networks” and another one that said “Disable local LAN access”. I unchecked both and disabled IPv6 on the Wi-Fi adapter as you suggested.

Now when I connect VPN, Wi-Fi stays connected and Windows doesn’t show the globe icon anymore. But I still can’t reach some websites — my personal browser tabs time out, while Outlook and our remote desktop over VPN seem fine. It’s like VPN blocks normal internet but corporate stuff works.
Technician avatar Technician
That behaviour is classic “full-tunnel VPN with strict DNS”. Your company is likely forcing all traffic (even personal browsing) through the tunnel. If DNS or routing is slightly off, it looks like “Wi-Fi drops when VPN connects”, but really the tunnel is just blocking non-corporate sites.

Step C — Check DNS and split tunneling behaviour
1) While VPN is connected, open Command Prompt and run:
  • ipconfig /all
Confirm that the active DNS servers now belong to your corporate VPN (often private IPs). That’s expected, but bad entries or old DNS can cause time-outs.

2) Run:
  • ipconfig /flushdns
  • ipconfig /registerdns

3) Try visiting a plain site like example.com and then a known internal site (like your intranet). If internal works and external doesn’t, the VPN policy is likely “no split tunneling” — IT wants all traffic to go through the tunnel and may block some categories.

4) If your VPN profile has a toggle for split tunneling or “Only send traffic for these domains through VPN”, enable it, then reconnect. Not every company allows this, but if they do, it’s the cleanest fix so Wi-Fi + VPN can coexist without breaking your personal browsing.
Customer
With the VPN connected, ipconfig /all shows DNS servers from our corporate network. After flushdns and registerdns, our internal apps are snappier, but some external sites are still slow or won’t load at all.

I don’t see any split-tunneling option in AnyConnect, so I guess IT locked that down. However, my original issue — where Wi-Fi disconnected when VPN connected — is mostly gone. Now it’s more like “internet is very flaky once VPN is on”.
Technician avatar Technician
Great, we’ve moved from total Wi-Fi drop to “VPN works but internet is flaky”, which usually comes down to MTU and protocol on Wi-Fi.

Step D — Change VPN transport & fix MTU so Wi-Fi stays stable
1) In the VPN client (or profile), see if you can switch between:
• UDP ↔ TCP for the tunnel
• Or between IPSec and SSL / “TLS” modes
Some home routers or ISPs don’t like IPSec over Wi-Fi and will silently drop fragmented packets. Switching to SSL/TLS over TCP often fixes “Wi-Fi drops when VPN connects” or random page time-outs.

2) On Windows, we can also shrink the MTU used over Wi-Fi so VPN packets fit cleanly:
  • Open Command Prompt as admin and run:
    netsh interface ipv4 show subinterfaces
  • Note the Wi-Fi interface name (e.g., “Wi-Fi”).
  • Then set MTU to something safer like 1400:
    netsh interface ipv4 set subinterface "Wi-Fi" mtu=1400 store=persistent

3) Reboot, reconnect to Wi-Fi, then connect VPN and test a few sites plus your corporate apps. A slightly smaller MTU often stops VPN from killing Wi-Fi or making some websites hang on load.
Customer
My profile in AnyConnect lets me switch from “DTLS/UDP” to “TLS only”. I changed it to TLS, ran the MTU command to set Wi-Fi to 1400, then rebooted.

Now when I connect to the VPN on Wi-Fi, the connection stays up, no globe icon, and both internal sites and normal internet pages are loading fine. I tried a couple of speed tests and a Teams call, and nothing dropped. This is way better than before when Wi-Fi would drop every time VPN connected.
Technician avatar Technician
Excellent — that tells us your home Wi-Fi and router are fine, and the fix was aligning VPN protocol + MTU with what your network supports.

For future reference (or if you use VPN on your phone/tablet too):
• On Android VPN apps, there’s usually a setting to switch between UDP and TCP, or choose OpenVPN vs WireGuard. If Wi-Fi drops when VPN connects on Android, pick TCP or WireGuard and disable any “block connections without VPN” option temporarily.
• On iOS/iPadOS, if Wi-Fi disconnects when you enable a VPN profile, deleting the old profile, resetting Network Settings, and reinstalling the VPN app clears a lot of glitches.
• On Mac, similar issues can be fixed by removing old VPN configurations in Network settings and ensuring Wi-Fi is at the top of the service order so it stays primary when VPN connects.
Customer
Good to know. I sometimes use the same VPN profile on my iPhone, so I’ll keep that in mind if it starts acting up there too. For now, the main thing is my work laptop finally stays online over Wi-Fi when VPN connects.

Is there anything I should tweak on the router itself so this doesn’t come back, or is it mostly just a laptop/VPN setting issue?
Technician avatar Technician
Great question. Since Wi-Fi only dropped when VPN connected, we’ve mostly solved it on the laptop/VPN side, but a few router tweaks help keep things stable:

• In the router’s admin page, make sure VPN passthrough (IPSec/PPTP/L2TP) is enabled if available, and that there’s no special rule blocking VPN ports.
• Turn off overly aggressive QoS / traffic shaping rules that might throttle or drop encrypted VPN traffic on Wi-Fi.
• Keep the router’s firmware updated so bugs that break VPN over Wi-Fi are patched.
• Avoid using very old 2.4 GHz-only equipment for heavy VPN use; if possible, connect over 5 GHz Wi-Fi or Wi-Fi 6 for better stability.

On the laptop side, keeping your Wi-Fi drivers, VPN client, and Windows updates current is the best defence against “Wi-Fi disconnects whenever VPN connects” returning.
Customer
I enabled VPN passthrough and updated the router firmware just in case. Everything still works — I can connect to the VPN on Wi-Fi, browse normally, and stay on calls.

This is exactly what I needed. Thanks for walking me through why my Wi-Fi dropped when VPN connected and how to fix it step by step.
Technician avatar Technician
You’re very welcome — glad we could get your VPN and Wi-Fi working together.

Summary: When Wi-Fi drops when VPN connects, fix it by updating the Wi-Fi driver, disabling power-saving, turning off overly strict VPN “block non-VPN traffic” options, disabling IPv6 if not required, adjusting VPN protocol and MTU, and keeping router firmware updated with VPN passthrough allowed. If you ever see your Wi-Fi cut out again the moment you start a VPN, you can open a chat with an expert and we’ll click through the settings with you in real time.

Quick answer: the accepted fix

Accepted fix when Wi-Fi drops when VPN connects: confirm Wi-Fi works normally without VPN, update the Wi-Fi adapter driver, disable power saving and unneeded IPv6, relax strict VPN kill-switch / “block non-VPN traffic” options, switch the VPN protocol (UDP↔TCP or IPSec↔SSL), lower the Wi-Fi MTU to around 1400, and keep the router firmware updated with VPN passthrough enabled so Wi-Fi stays stable while the VPN tunnel is active.

Why Wi-Fi disconnects when VPN connects (drivers, MTU, kill switch, router)

Most Wi-Fi drops when VPN connects problems come from how the VPN client rewrites routes and encrypts traffic, not from the ISP itself. When a VPN creates a secure tunnel, it installs a virtual network adapter, changes default gateways, and often forces all traffic through corporate DNS servers. Buggy Wi-Fi drivers, wrong MTU size, or a strict VPN kill switch can make Windows or macOS think there is “no internet” and drop the wireless connection.

Home routers can add to the issue. Some models partially block IPSec, L2TP, or OpenVPN over Wi-Fi, so packets get fragmented or dropped once the tunnel is active. The result looks like “internet disconnects when VPN is on” even though the Wi-Fi signal itself is fine. Breaking the path into pieces — device → Wi-Fi adapter → VPN client → router → VPN server — lets you see which layer is actually causing the VPN Wi-Fi disconnect.

How to tell if the problem is Wi-Fi, VPN client, or router

To quickly narrow down a Wi-Fi disconnects when VPN connects issue, start with simple tests:

First, connect the same device via Ethernet or a mobile hotspot and try the VPN. If VPN works there, then the server and your account are fine, and the issue is specifically VPN over Wi-Fi. Next, test Wi-Fi without VPN — if streaming and calls are stable, your basic wireless network is okay. Finally, connect VPN on Wi-Fi and watch closely: if Wi-Fi itself drops, focus on drivers, MTU, and power settings; if Wi-Fi stays up but websites fail, focus on VPN protocol, DNS, and router firewall/VPN passthrough.

Wi-Fi drops when VPN connects — quick troubleshooting tips

Make sure Wi-Fi is stable alone, then tune VPN protocol, MTU, and security options so they work together.

Fast path: test that Wi-Fi works without VPN → update Wi-Fi drivers and disable power-saving → relax VPN kill-switch / “block non-VPN traffic” settings → switch the VPN tunnel type (UDP/TCP, IPSec/SSL, OpenVPN/WireGuard) → lower the Wi-Fi MTU to avoid fragmentation → enable VPN passthrough and update router firmware. These steps fix the majority of cases where Wi-Fi disconnects whenever VPN connects on Windows, Mac, Android, or iPhone.

Disclaimer: This information is AI-generated and intended for general guidance only. For advice specific to your VPN provider, company security policy, and router model, please consult a verified expert on Whizz-Tech before making changes.

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FAQ

Why does my Wi-Fi disconnect every time I turn on my VPN?

Usually because of a conflict between the Wi-Fi adapter driver, the VPN virtual adapter, and your router. When the VPN connects, it changes routing and DNS, and a buggy driver or strict kill-switch policy can cause Windows or macOS to mark the Wi-Fi as having “no internet” and drop it. Updating drivers, disabling power saving, relaxing “block non-VPN traffic” options, and changing VPN protocol/MTU typically stop Wi-Fi from dropping when VPN connects.

How do I fix Wi-Fi drops when VPN connects on Windows 11?

On Windows 11, start by updating your Wi-Fi driver, turning off “Allow the computer to turn off this device to save power”, and running a Network reset. Then disable unnecessary IPv6 on the Wi-Fi adapter, relax any VPN kill-switch / “disable local LAN access” options in the VPN client, switch the VPN from UDP to TCP (or to SSL/TLS), and lower the Wi-Fi MTU to around 1400 using netsh. These steps fix most “Wi-Fi disconnects when VPN connects” cases on laptops.

Why does my company VPN work on mobile data but not on home Wi-Fi?

If your company VPN only works on mobile data, your home router or ISP may be blocking or throttling the VPN protocol (IPSec, L2TP, or some SSL VPN ports), or mishandling large encrypted packets. Enabling VPN passthrough in the router, updating its firmware, changing the VPN to use a different protocol/port, and lowering MTU on the device usually resolves this so the VPN works over home Wi-Fi as well.

Is it safe to change VPN protocol or MTU to stop Wi-Fi disconnects?

Yes, in most cases it is safe — many VPN providers even recommend switching between UDP/TCP or OpenVPN/WireGuard if you have stability issues. Lowering MTU slightly (for example to 1400) simply makes packets smaller so they’re less likely to be fragmented by your router or ISP. As long as you’re using a supported protocol from your VPN or IT department, adjusting these settings is a common way to fix Wi-Fi dropping when VPN connects without weakening encryption.

Sources

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