@Ivaylo I see and yes, my PC port is 1 Gbps. Mobo is Strix X370-F Gaming.

@Ivaylo Yup. It dropped to 100 after reboot. I'll ask my ISP to check the cable tomorrow. Are you sure it's not the firmware or something? I haven't seen much about my model (v3.20) on the internet.

@Ivaylo Alright.. hard reset brought it back to 1000Mbps Full Duplex but I believe if I reboot now it'll drop down to 100 again.

@Ivaylo Idk how I'm supposed to test this but here's what I did. I picked a spare Cat 5e cable and plugged it from my router's WAN port to my PC. I then checked the adapter status for speed and it's...

@Ivaylo Says, "Model:Archer C6(US) Ver:3.20" on the sticker and the firmware is 1.0.5 Build 20201117 rel.41066(5553), which is up to date. You mean test the WAN port with a different cable?

Model: Archer C6 (US) Hardware: v3.20 Firmware: 1.0.5 Build 20201117 rel.41066(5553) As mentioned in the title, my router's WAN Port Negotiation Speed drops from 1000Mbps Full Duplex to 100Mbps Full...