Network troubleshooting technician providing live chat help

Joe B.

Reviewed for technical accuracy

Specialities: Home networking, Verizon Fios ONT, Wi-Fi routers (G3100/CR1000A/third-party), DHCP & IP configuration, ISP setup

Fix Verizon ONT not connecting — Fios ONT no internet, LOS/FAIL light on, DHCP/WAN not pulling IP

Technician avatar Technician
Hi! We’ll get your Verizon Fios ONT not connecting issue fixed. Quick picture of your setup helps. Do you have the ONT connected via Ethernet to a Verizon router (G3100/CR1000A) or a third-party router? On the ONT, what do the lights show — PON solid green, LOS red, or FAIL red? And on the router’s WAN/Internet page, does it pull a DHCP address from Fios or show 0.0.0.0?
Customer
It’s Fios. The fiber goes to the ONT in the basement, then Ethernet to a G3100. Wi-Fi shows connected but no internet on all devices. On the ONT I see green Power and PON, no red LOS, but sometimes a brief FAIL light after power cycles. In the G3100 admin the Internet status says Disconnected and WAN IP is 0.0.0.0.
Technician avatar Technician
Thanks — good detail. With Fios, a common reason for ONT connected but no internet is the router not obtaining a DHCP lease from the ONT (shows 0.0.0.0). Other causes: ONT power issues (PSU/BBU), Ethernet from ONT going to a LAN port by mistake, or a stale Fios lease after swapping routers (sometimes needs a proper DHCP release or wait). Since your PON is green and no steady LOS, the fiber signal is likely OK — we’ll re-establish the ONT→router link and force a fresh WAN lease.
Customer
The Ethernet from the ONT is in the blue WAN port on the G3100. I did a couple restarts but it still won’t grab an IP. We did replace a router last week; not sure if we ever did a WAN DHCP release.
Technician avatar Technician
Perfect — let’s do the clean sequence Fios expects.

Step A — ONT power and clean reboot
1) Locate the ONT power supply (PSU) or older BBU. Unplug it from AC for 60–90 seconds (if there’s a battery, remove or disconnect it so the ONT fully shuts down).
2) Plug PSU back in; wait until ONT Power and PON are solid green and LOS is off.

Step B — Router WAN lease refresh
3) With the ONT up, power the G3100 off for 30 seconds, then on.
4) In the G3100 admin go to Internet settings and click DHCP Release (if available), then DHCP Renew. If Release is greyed, just Renew after the reboot.
5) Confirm the WAN now shows a public IPv4 address (not 0.0.0.0). If it still shows 0.0.0.0, leave the router powered off for ~2–5 minutes, then power it on so the ONT offers a fresh lease to the first device it sees.

Tell me what the WAN page shows after this.
Customer
After unplugging the ONT PSU and rebooting the G3100, the WAN now shows a real IP and Internet: Connected. But phones still say “connected, no internet” until I toggle Wi-Fi. A Windows laptop also shows limited connectivity.
Technician avatar Technician
Great — the ONT↔router link is back. Now refresh devices so they pull the new DHCP/DNS info from the G3100.

Step C — Fix “Wi-Fi connected, no internet” on devices
• On Windows: set IPv4 and DNS to Obtain automatically → run ipconfig /release, ipconfig /renew, ipconfig /flushdns (Admin Command Prompt).
• On iOS/Android: forget and re-join the SSID or toggle Airplane mode for 10 seconds.
• If you used custom DNS on any device (or in the router), revert to automatic or known-good DNS temporarily to test.

If all devices work on Wi-Fi but wired PCs drop, we’ll check the Ethernet side next (ONT→router WAN is separate from LAN switch ports).
Customer
Toggling Wi-Fi helped. Most devices are back online. One desktop on Ethernet still randomly drops from games, though web pages work. The ONT lights stay normal (Power/PON green, LOS off).
Technician avatar Technician
Copy. Let’s harden LAN stability:
• Verify the PC is in a LAN port on the G3100 (not the blue WAN). Try a different LAN port and a known-good Cat5e/Cat6 cable.
• Update the G3100 firmware (auto-updates usually enabled) and the PC’s NIC driver.
• If you’re using MoCA/coax extenders, test with a direct Ethernet run to rule out MoCA noise.
• Temporarily disable VPN/security software — some cause “internet drops” during games even when browsing is fine.

If multiple Ethernet devices drop simultaneously, we’d look at QoS and router CPU usage; if only this PC drops, it’s local to that machine or cabling.
Customer
Swapped the cable and updated NIC + router firmware. Wired drops stopped. Everything is stable now. Anything else I should change so the Fios ONT no internet issue doesn’t come back?
Technician avatar Technician
Nice! Final tweaks so Verizon ONT not connecting doesn’t recur:

• Keep the ONT PSU/BBU on a small UPS; power dips can leave ONTs half-booted (brief FAIL light).
• If you ever swap routers (e.g., to CR1000A or third-party), power off the old router, reboot the ONT, then power up the new router so it gets the first DHCP lease from the ONT.
• Use Ethernet from ONT to router for internet; only use MoCA/coax for TV where required.
• Review the router admin: disable unnecessary remote management, keep auto-updates on, and document your Wi-Fi/guest SSIDs.
• If you ever see solid LOS red or persistent FAIL on the ONT, that’s fiber/ONT trouble — usually needs a Verizon tech visit rather than a router change.
Customer
Got it. UPS for the ONT and the reboot order noted. For future reference, if I replace the router again, do I need to call Verizon to release DHCP?
Technician avatar Technician
Usually no call is needed — a clean ONT reboot with the new router powered off is enough. Best practice:
1) Power off old router → reboot ONT (PSU/BBU unplug 60–90s) → power on new router → check WAN shows a fresh DHCP IP.
2) If WAN still shows 0.0.0.0, try the router’s DHCP Release/Renew button once the ONT is fully up.
3) In rare cases, wait out the lease for a bit or contact Verizon to manually release it. But for most homes, the above sequence works.
Customer
Makes sense. Everything’s working now on both Wi-Fi and Ethernet. Thanks a ton for the Fios-specific steps.
Technician avatar Technician
You’re welcome!

Summary: For Verizon ONT not connecting or Fios no internet: verify ONT lights (Power/PON green, LOS off), reboot the ONT PSU/BBU, connect ONT → router via Ethernet to WAN, then force a fresh DHCP lease on the router. Refresh device DNS/IP and keep firmware updated. If LOS/FAIL persists, schedule a Verizon tech — that points to fiber/ONT, not Wi-Fi settings. If you want, open a chat and we’ll walk it live.
Customer
All set. Appreciate the help — saving this checklist for next time.
Technician avatar Technician
Glad to hear it. If a friend says their Fios ONT won’t connect or their Verizon router shows no internet, share this page — or start a chat and an expert will trace the ONT, router, and devices with you.

Quick answer: the accepted fix

Accepted fix when Verizon ONT is not connecting: reboot the ONT PSU/BBU so PON is solid and LOS is off, ensure the ONT’s Ethernet goes to the router WAN port, then use the router’s DHCP Release/Renew to get a fresh IP from Fios. Finally refresh device DNS/IP so “connected, no internet” clears.

Why a Fios ONT shows no internet (PON/LOS/FAIL, DHCP, Ethernet, MoCA)

Most Verizon ONT not connecting cases are either a stale DHCP lease after a router swap, an ONT that didn’t fully reboot after a power blip, or the Ethernet handoff from the ONT landing in the wrong port. Check that the ONT’s PON is green, LOS is off, and the router’s WAN page shows a valid IP. Coax MoCA is for TV; internet should come from the ONT’s Ethernet to the router’s WAN.

If FAIL is red or LOS lights, that indicates an ONT/fiber problem that usually requires a Verizon technician. If WAN is connected but devices say “Wi-Fi connected, no internet”, refresh device DNS and DHCP or remove custom DNS temporarily.

How to tell if it’s the ONT, the router, or your devices

To quickly narrow down a Fios ONT no internet issue: verify PON and LOS on the ONT, then log into the router to confirm a live DHCP WAN IP. If the router has internet but a specific laptop does not, reset that device’s network adapter/DNS. If the router shows 0.0.0.0, focus on the ONT reboot and WAN lease renew process.

Verizon ONT not connecting — quick troubleshooting tips

Reboot the ONT PSU/BBU first, then refresh the router’s WAN lease and device DNS.

Fast path: ensure ONT power is stable → confirm PON green, LOS off → ONT Ethernet to router WAN → reboot ONT then router → press DHCP Release/Renew in the router → refresh device IP/DNS. Keep firmware auto-updates on and protect the ONT with a small UPS to avoid intermittent Fios no internet issues after power flickers.

Disclaimer: This information is AI-generated and intended for general guidance only. For advice specific to your ONT model and Verizon account, please consult a verified expert on Whizz-Tech before making decisions.

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FAQ

What do PON/LOS/FAIL lights on a Verizon ONT mean?

PON solid green = fiber link is good. LOS red = loss of signal (fiber issue). FAIL red = ONT fault and typically needs Verizon service if it persists after a full PSU/BBU reboot.

Do I need to call Verizon to release the DHCP lease when I change routers?

Usually no. Power off the old router, reboot the ONT PSU/BBU, then power on the new router and press DHCP Release/Renew in the router. In rare cases you may wait out the lease or contact Verizon to release it manually.

Can I use MoCA/coax for my internet from the ONT?

For modern Fios speeds, Verizon hands off internet via Ethernet from the ONT to the router’s WAN port. MoCA/coax is typically for TV set-tops or LAN extenders, not the ONT internet handoff.

When should I schedule a Verizon technician?

If LOS or FAIL remains red after an ONT power cycle, or PON won’t go solid green, that indicates a fiber/ONT issue that remote steps won’t fix — book a Verizon visit.

Sources

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