Need help ASAP please

[Anonymous_2180]

So I just got Fios and got the gigabyte speeds. Since techs aren’t allowed in my home I did self install. After installing the G3100 router I noticed horrible WiFi speeds. Only 30down and 40up. I disabled the SON feature as some had suggested but I would only get 60 download on the 5g band. I checked a wired connection and noticed I was only getting 90 download. I called tech support and they said it is reading fine on their end and that it is my device. So I decided to troubleshoot the problem myself as I know it’s not my devices. The first thing I did was purchase a new CAT6 cable and ran it from the ONT box to the router. 45.00 later I was good. I was getting 560down and 480 up over WiFi. Direct connected I was 970down and 880 up. I was happy. Than I woke the next morning to the slow WiFi. I checked the wired connection and sure enough it’s slow. I than decided to go into the routers interface and take a look around. I found the problem. The issue is in the settings tab under port configuration. The WAN port was set to auto and was only allowing 100mbps full duplex. I manually switched this to 1000mbps full and I’m all good again. The next morning it’s back to 100. So I call tech support again and they believe it to be the cable even though I explained I replaced the cable as it was my first thought too. They had me do a factory reset on the router and told me not to change anything and see if it defaults back to 100. Not 2min after I hung up it was back to 100. Now I can’t even manually change it to 1000 because if I do it says wan is disconnected and I have no internet.  I don’t know what to do. Do I spend another 40.00 on another cable and run it again. With my ONT outside this was a pain in my butt the first time and I hate throwing money away. Could this be something else?  Any help would be greatly appreciated. Thank you!

[Edg1 · Accepted solution]

If the ethernet cable has been replaced then the issue could be with the G3100. I would call and have them ship you a replacement. If that still doesn't work then it could be the ONT. Luckily your ONT is outside and can be easily replaced by a technician.