Help! New PC Won’t Connect to Ethernet

Hey everyone! I'm really stuck here. I've recently built a new PC, and everything seems to be working perfectly, except I'm having a major issue with the Ethernet connection. While the Ethernet port on the back of my motherboard shows green link lights, I'm still not able to access the internet. Currently, the only way I can connect is by tethering my phone to the PC via USB, which isn't ideal.

I've tried a few things already: the Ethernet cable works fine on another laptop (Layer 1 test). I also updated the BIOS to the latest version but it didn't help. I downloaded the LAN drivers directly from the vendor's website, but clicking on the setup doesn't do anything; no installation wizard pops up. I even tried getting the drivers from Intel's site, but it tells me "no Intel network connections found on this computer, no drivers were installed."

I made sure Windows is up to date and even did a fresh install. Just to troubleshoot further, I added an old network interface card (NIC) from another PC that I know works, but I ran into the same issue with driver installation - it wasn't recognized at all. Plus, I've noticed that some USB ports aren't functioning either. At this point, I'm leaning toward the motherboard being faulty, but I'm not entirely sure since it could just be driver-related issues. Here are my specs: Asus Rog Crosshair X670e Hero motherboard, AMD Ryzen 7 7800X3D CPU, NVIDIA GEFORCE RTX 3080 GPU, 32GB Corsair Dominator RAM, and an 850W Asus gold PSU.