Ethernet speed keeps changing to 10mbps after a Disconnect/Disabling the ethernet adapter from Windows!

I too have exactly the same issue with my realtek gaming 2.5gbe family controller. I have changed network cable several times, tried different drivers. My router is capable of 1000/1000 and will sometimes connect at that speed but all of a sudden my entire internet goes slow ... I mean unusable slow and I check and my network is running at 10/10. I have tried cat 7 cat 6e cat 6 cat 5. I am lost and at the end of my tether. My PC will load windows and connect at 1000/1000 or sometimes 100/100 or sometimes 10/10. But when it connects at 1000/1000 it will randomly drop to 100/100 or even 10/10 and then will not go back to 1000/1000 until a reboot or a physical disconnect and reconnect of the network cable at either the router end or the PC end. I have had this problem for months and unable to resolve it.

Pretty sure this is a Windows 11 issue.

I have endless issues with my Intel Ethernet Controller I225-V adapter.

It's a 2.5 Gbps device plugged into a 2.5 Gbps switch and it forever changes it's speed down to 1000 Mbps and then down to 100 Mbps (even10 Mbps) and then will just randomly stop working (the connection will just drop and reconnected for a few minutes).

I have even forced the driver to "2.5 Gbps Full Duplex" but it will just eventually ignore that setting and revert it back to "Auto Negotiation" on its own.

Hi,

If it works with Kubuntu Linux, it could be a driver problem with your network card.

Is the network card, Realtek RTL8111H, integrated into the motherboard or is it an external PCIe network card?

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: Energy Efficient Ethernet(EEE),Green Ethernet,Power Saving Mode etc. Then try again.

If the situation does not change, go to the website of the motherboard manufacturer, download and install the latest available updated drivers for the LAN card and Chipset. Also make sure you are running the latest BIOS version.

same issue here, speed drops from 300mbs to 10, i use a a script, flushing dns and winsock reset

ipconfig /flushdns

ipconfig /registerdns

ipconfig /release

ipconfig /renew

netsh winsock reset catalog

netsh int ipv4 reset reset.log

netsh int ipv6 reset reset.log

makes it bearable. bad driver from realtec

I agree with this, since i upgraded from windows 10 to windows 11 i started facing this problem where my internet connection would be capped at 10mbps from 1gbps randomly and it wouldn't fix no matter how much i tried, but it will randomly fix itself and go back to 1gbps. I thought this was a Windows 11 problem solely so i decided to go back to Windows 10 again but this problem wasn't fixed, i have a lot of things from the internet to fix it but nothing seems to work and it happens very randomly. I even thought that it was my router(Archer C6) overheating and even turned off my router for a long time for it to cool down, and after i turned on my computer it was still capped at 10mbps again, i upgraded and downgraded from a lot of Realtek drivers and even consulted my ISP and they indicated that this is something that has to do with windows itself and they cannot fix it. It happens randomly and frequently and my internet gets so bottlenecked when it switches to 10mbps that its almost impossible to do basic tasks as watching YouTube,
I hope to receive a solution about this from the Microsoft team as soon as possible since its very troublesome if this happens during important times.