Question Why can I not exceed 100mbs on a 400mbs plan?

[MiscWorker]

Specs
Arris TG2482
B450 GAMING PLUS (MS-7B86)
Microsoft Windows 10 Pro (64-bit)
NVIDIA GeForce GTX 1060 6GB
Intel® Gigabit CT Desktop Adapter
Realtek PCIe GbE Family Controller
SeaSonic 520 W 80+ Bronze Certified Fully Modular ATX Power Supply

I recently switched to a 400mbs plan, but my computer can only receive 100mbs when plugged in through ethernet (no wifi on board). I am using a cat6 cable. The realtek adapter listed above is integrated into my motherboard. It lists on its status that it is sending 1gbs, but it is not. I've fiddled with my router which does allow 1gbs in all four of its ports.

So I thought it was my adapter, so I got the intel adapter listed above, and it is suffering from the same problem after I (think) I updated its drivers manually, because the .exe from intel will not recognize that the adapter is plugged in. Besides, it should work out of the box anyway, according to Intel... I really don't know what to do. Please help me.

 

[rgd1101]

just your computer having issue?

 

[bmockeg]

Is there a setting in the gateway to change the port speeds that may be set to 100?

 

[Alabalcho]

When you go to Control Panel, Network Connections, and double-click on the adapter, what connection speed you see? Where does the other end of that cable go?

 

[MiscWorker]

just your computer having issue?

Is there a setting in the gateway to change the port speeds that may be set to 100?

When you go to Control Panel, Network Connections, and double-click on the adapter, what connection speed you see? Where does the other end of that cable go?

It appears to be only my computer, considering the other computer in the house got the 400mbs instantly with no prior setup. Literally same port in the router and same cord, no prior setup, and speedtest.com showed 400mbs+. Different specs though.

The port speeds are on auto on default. Changing the port speeds to 1000, full duplex, etc. does nothing. If I set it to 100, it actually makes the speed slower, and same for 10.


Same result for both adapters I have: it lists 1gbs. The router's status lists 1gbs as well. Pretty much EVERYTHING that can list a current set speed says 1gbs, except it's not.

Edit: Thank you for the swift responses, by the way. I appreciate the attention and concern.