This seems like a One UI 7 + WireGuard compatibility bug. You're not alone — others have had issues with network devices going grey or becoming unreachable over VPN after the update.
Here’s what you can try:
1. Switch WireGuard from Always-On to Manual (temporarily) and see if the printer works fine when you toggle it manually.
2. Try using a local IP for the printer instead of hostname — One UI 7 might be bugging out on DNS over WireGuard.
3. In WireGuard settings, enable Allowed IPs: 0.0.0.0/0 if it isn’t already — this makes sure all traffic goes through the tunnel (if that’s what you want).
4. If your printer is on the LAN, try setting a split tunnel config so local traffic doesn’t go through WireGuard (e.g., exclude your local subnet).
And yeah, it’s kinda sus that something this basic broke after an update. Might be worth reporting to Samsung Members or checking if others are having similar problems with WireGuard and printers specifically.