Quest 3S can't detect my PC through Air Link (USB Link works, Steam Link has the same issue)

Hi everyone,

I'm hoping someone has run into this before because I'm running out of ideas.

My setup:
Headset: Meta Quest 3S
PC: Ryzen 5 3600, Radeon RX 6600 (8 GB), 48 GB RAM}
Router: ZTE (ISP-provided)
PC connection: Ethernet}
Quest connection: 5 GHz Wi-Fi
Both devices are connected to the same router.

The problem: When I open Air Link on my Quest, my PC simply doesn't appear in the list of available computers.

However: USB Link works perfectly. The Meta Quest app on my PC recognizes the headset when connected with a cable. Steam Link also fails, saying that my PC and headset need to be on the same local network. Last week it worked fine, but when i went to play VRChat today, it failed me like this

Things I've already tried:

Restarted the Quest, PC, Meta Quest app, and router.
Confirmed the Windows network profile is set to Private.
Allowed all Meta/Oculus services through Windows Firewall.
I don't use any third-party antivirus.
Verified that AP Isolation / SSID Isolation is disabled.
Confirmed the Quest is connected to the 5 GHz network (not the guest network).
Confirmed the PC is connected to LAN1 on the router.
Checked that the Quest and PC receive IP addresses in the same subnet (same first three octets).
Removed and retried Quest Link pairing.
Restarted the Meta/Oculus services.

At this point I'm not sure what else to check.

Has anyone experienced this before, or knows of another setting (Windows or router-related) that could prevent local network discovery while still allowing USB Link to work?

Any ideas would be greatly appreciated.