Wired Connection Problem: Gig Connection, G3100 Router, 300+ mbps wireless but 100 mbps max wired

[bdevilu]

I have the Verizon Gateway router (G3100) installed on the second floor in the center of our two-story house.  ONT is on the first floor in the garage quite a distance from the router and is connected by COAX and Ethernet cable into the WAN port.  The cable distance between ONT and router might be over 100 feet but I doubt it is over 200 feet.  I also have a FiOS One STB connected via coax on the first floor much closer to the ONT.  Verizon speed tests indicate the router is getting internet at 900-950 mbps download and upload consistently.  Wireless speeds are 300 mbps upload and 150 mbps download fairly consistently, and wireless coverage from the router are good. 

However, for some reason, no matter what CAT 5 cable I use and no matter what LAN port of the router I connect to, I cannot get wired speeds above 100 mbps for any device.  Wired speed almost seems like it is "capped" at 100 mbps for some reason.  Equally strange (to me, anyway): a just-purchased 100 foot CAT 6 cable gets no better than 10 mbps.  Given that we have multiple adults and children streaming video all day long, we are trying to improve our wired connections so they at least approach the Gig service we're paying for.  Any suggestions are appreciated as the Verizon troubleshooter is not currently functioning.

[appDev]

you should run a 'wired' speed test directly from the ONT.

If you're still getting less than ~750, you need VZ to take a look.

But given your wireless speeds are higher, i am thinking it could be your ehternet card on whatever machine you are testing from. Is that a gig-speed NIC card?

[Cang_Household]

I suggest you to check the ethernet link protocol at the router. If you know how to read the back LEDs for speed indications, check whether the connection is 100Base-T or 1000Base-T. If you don't know, log into your router web configuration interface and go to Advanced -> Port Configuration. The Ethernet port should say 1000Mbps Full Deplex. 

Definitely check your NICs too and software configuration to make sure it is 1000Mbps.

Do you have intermediate connectors (e.g. wall jacks, couplers, or even layer 2 devices) between the router ethernet ports and the device? Check all connectors as where because mis-wiring them can cause slower speed.

[bdevilu]

Thank you for the suggestions.  I checked the Ethernet port configurations on the router and the WAN and all LAN connections are showing as "1000 Mbps Full-Duplex".

I just connected my laptop with a USB-C Ethernet adapter by CAT 5 cable to one of the LAN ports and ran the Verizon speed test and lo and behold, I now am getting 900+ mbps upload and download.  I made sure to turn my wifi card off before running the test.  

Getting those speeds would seem to rule out any problem in the long cables into the router, right?  So I'm going to check our couple of outlets upstairs with wired Ethernet plugs in case they've gone bad.

Thanks for the help.

[Cang_Household]

Sometimes the ethernet jacks will limit the speed if it is wired incorrectly, or if you wired only two twisted pairs instead of four.

If that's not the problem, I may need a more detailed description of how your network is connected.

[tecnotes]

I have the exact same problem.  I am receiving GB service to my G3100 WAN port, but no matter what i set any of the ethernet ports to, they will not go higher than 100mbps.  I tested with a brand new factory made cat6 cable.  does this appear to be a faulty router?

[Cang_Household]

You should not be setting the router Ethernet ports to anything other than Auto. The Ethernet controller in the router will negotiate with its counterpart in your device to determine the link speed. Can you double check whether your device's NIC is capable of 1000Mbps? Thanks.

Also, can you check your device's network interface settings?

For 1000Mbps, CAT6 cable is already overkill. CAT5e is perfectly fine. CAT6 can support up to 10Gbps.

[tecnotes]

OK, yes, I am using CAT 6 cable, but i don't think that is a factor here, agreed?  I have set the dropdown for LAN port config back to auto and the connection is still listed as 100mbps. I connect with my laptop which does have a GB capable NIC.  I also connect my Amplify mesh router, which is ultimately what i plan to bridge to the FIOS router, but I'd rather not get into that because it will take us off track.  Bottom line:  I have GB service to the router and 100mbps on the wired LAN ports no matter what i try.  I suspect a faulty router, but i remain openminded to any reasonable input.  Thank you!

[Cang_Household]

Just to increase the sample size, do you have another device that has a gigabit NIC? Can you use the same CAT6 cable to connect that device to the G3100?

[tecnotes]

Effectively I have tried another GB capable device because the Amplifi HD is GB capable, but I will look to find another device to test as well...

[Cang_Household]

Amplify HD does have gigabit Ethernet ports. I do know a way to test whether the Ethernet controller for G3100's LAN ports are broken. Can you temporarily unplug the WAN Ethernet from the ONT and plug the CAT6 cable into the WAN port for now? You just need to check whether the upper LED on the WAN port lights up, if so, that means the CAT6 cable is good and the link is 1000Mbps, if not, we need to investigate the issue further. Because the 4 LAN ports on G3100 is backed by one Ethernet controller, while the WAN port is backed by a separate Ethernet controller, this method should work.

Don't change any settings through the web interfaces, just check the port LEDs for now. Because we are only concerned about the link speed, we don't need to worry about network connectivity.