I have Frontier Fiber service advertised at 1 Gbps, but since installation my connection usually runs at roughly 95 Mbps. Occasionally, restarting the ONT and router brings it back to around 950 Mbps, but the faster speed only lasts anywhere from a few hours to a couple of days.
Frontier says the issue is probably my third-party ASUS WiFi 6 router and wants me to use their Eero equipment instead. However, I have tested the connection with my computer connected by Ethernet directly to the ONT, bypassing the router entirely, and I have also tried different points in the wired setup. The result is still inconsistent. My computer is always connected over Ethernet, and the adapter is configured for 2.5 Gbps full duplex.
A technician is scheduled to inspect the service, and I would like to collect useful evidence beforehand. What router, ONT, adapter, or connection-status information should I record to demonstrate whether the problem is with my equipment or with the fiber service itself?
5 Answers
A speed consistently just below 100 Mbps often points to a physical Ethernet link negotiating at 100 Mbps instead of 1 Gbps. Check the negotiated link rate on both ends, inspect or replace every cable, and remove the splitter or any intermediate switch for testing. Use Auto Negotiation rather than forcing 2.5 Gbps full duplex unless the adapter and device on the other end both support it. A damaged cable or port can sometimes behave intermittently, although a link that occasionally reaches 950 Mbps makes it less conclusive.
It is still worth temporarily using the provider's equipment if they will let you test it without permanently exchanging your router. If the same slowdown occurs with their Eero and a wired computer, that gives you strong evidence for the service or ONT. If they insist on taking your router, photograph the serial number and make clear that you want a test rather than an equipment replacement.
ONTs can become unreliable when they run hot, so checking ventilation is reasonable. A fan aimed at it during a slowdown could be a useful experiment, but the technician should still check the optical power levels, error history, Ethernet negotiation, and whether the ONT is losing its provisioned profile. Router logs alone probably will not prove much if the problem also happens with a direct ONT connection.
Look at the router's WAN status page while the connection is working and while it is slow. It should show the WAN Ethernet link speed and may have traffic or error counters. If the WAN link remains at 1 Gbps or faster while a directly connected computer still gets about 95 Mbps, the issue is likely upstream of the router. If the WAN link has fallen to 100 Mbps, focus on the ONT-to-router cable, connectors, and ports.
The most useful test is to connect one computer directly to the provider's handoff point and run repeated wired speed tests while the problem is occurring. If it still drops to about 95 Mbps with the router completely removed, your ASUS router is not the cause. Record the date, time, test server, result, and whether a reboot temporarily restores full speed. Also ask the technician to test from the ONT and check the optical signal and ONT logs.
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