Network Adapter stuck at 100mbps

I have had the same issue with one of my 10 PCs, and it is the only one with this issue. I have used the same cable and port on this one switch on other PCs with not issue. I have booted the problem PC with a Linux live disk and I get full 1gbps with that. I have tried other cables etc. and given that Linux is not limited to 100mbps on this fake machine I can say, after 40 years as a software developer, that it is some Windows specific setting, not the switch port, not the cable, not the port on the PC, it is some conbination of Windows settings which is not ready to find. I thought it was a driver link speed setting, but after changing this still no joy.

It's an old thread, but I just ran into a similar issue with my laptop and was reading through this to try and figure it out. I couldn't leave without saying something. As an A+ Certified technician, and an MCSA certified professional, in my 20 years in IT, I have never seen a second monitor cause a network adapter to downgrade the connection to 100 mbps.

I understand you have a script and a checklist that you have to run through, but that step doesn't make any sense at all. I think your procedures need to be reevaluated.

Is the Realtek Gaming 2.5GbE Family Controller built into the motherboard or is it an external PCIe network card?

Is the PC network cable connected directly to the LAN port of the router or through the ethernet wall socket or something else? "Speed & Duplex" must be set to Auto Negotiation. Go to Device Manager>network adapters,right click on your network adapter in use>Properties,click on Power Management tab,uncheck the checkbox:"Allow the computer to turn off this device to save power". Click on the Advanced tab and disable any options related to energy saving: Power Saving Mode, Energy Efficient Ethernet(EEE), Green Ethernet, Advanced EEE etc.

If you haven't already, try switching your network cable.

I forgot to follow up on this question.

So, after failing to get any help here, I went to TP Link support and had a long email exchange that led to the weird conclusion that my Ethernet cable might have some problems. If it was it, the router or the Lan port I haven't figured that one out.

Regardless, tested with a 6a cable, it worked flawlessly and has been working well for some months now.

My best advice is contacting your router's support team or your Mobo/Ethernet card support to see if they can figure out or suggest a problem fix. TP Link was great and has even allowed me to email the same person back if needed, so try your luck outside of this forum.

I honestly think you're exaggerating and dramatizing a situation where I have specified from the beginning what I have tried and that, with this setup, has worked for more than a year till something software wise happened. and as i also said before, the problem has temporarily been solved before going down again. monitors aren't a problem, or anything else connected, it is specifically an internet problem.

In fact, after I installed the driver from Gigabyte and reset the adapter, I had it try to shut down my network again, which I quickly solved temporarily by changing the "Speed and Duplex" setting. Seems to happen a while after I open some online program like Steam (but not firefox). There's dozens of people that have raised this issue before with 0 working solutions due to a lack of actual help from your guys side, so I ask you politely, please stop dancing around the issue and give me concrete possible solutions with all the information I've given you without raising more problems that have been discarded for not being interference's.