Question network drops to 100 mbps at bootup (not everytime...)

[shadowcat777]

I have a internet speed of 500/250 with router and is using windows 11 on my system. My problem is that
sometimes when I boot up my PC the internet speed is capped at 100 mbps. To fix this I have to replug my ethernet cable, and it works properly at 1gbps.
This never happened when I was using Kubuntu however. at times I also experience websites loading slower than usual.
Accordingly to Device manager my network is working properly. I have tried a few tweaks but havnt solved the problem.
I also bought a new cat6 cable but the problem continued. What might be the cause to this, and is there a fix ?
My motherboard is a B550-plus and in Device manager my network is= Realtek PCIe 2.5 GbE Family controller.
EDIT: I have tried to change in the "Speed & Duplex " also "Wake on "-stuff in the device manager. but problem consist
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[kanewolf]

I have a internet speed of 500/250 with router and is using windows 11 on my system. My problem is that
sometimes when I boot up my PC the internet speed is capped at 100 mbps. To fix this I have to replug my ethernet cable, and it works properly at 1gbps.
This never happened when I was using Kubuntu however. at times I also experience websites loading slower than usual.
Accordingly to Device manager my network is working properly. I have tried a few tweaks but havnt solved the problem.
I also bought a new cat6 cable but the problem continued. What might be the cause to this, and is there a fix ?
My motherboard is a B550-plus and in Device manager my network is= Realtek PCIe 2.5 GbE Family controller.
EDIT: I have tried to change in the "Speed & Duplex " also "Wake on "-stuff in the device manager. but problem consist
//

99.99% of the time it is a suspect cable. Get a factory made 100% copper, cat5e or cat6a round cable with 22 to 24GA wire. I like these -- https://www.amazon.com/Monoprice-Flexboot-Cat5e-Ethernet-Patch/dp/B00KWS7GAC?th=1

 

[bill001g]

2.5g port seem to have a lot more problem with cables that are slightly out of spec than 1gbit ports.
In any case as kanewolf says it is almost always a cable. Check there is no green power setting but even that mostly causes issues on longer cables.