As far as I’m aware Mint is actually Ubuntu with snaps ripped out, so I don’t think that’s it. Firefox, if I’m not mistaken is just installed from the firefox package, and not containerized using snap or flatpaks.
Did you get any response from the Mint community, @brandon?
One way to test this is to try librewolf:
If it works in librewolf by this method, then maybe they really did find a way to screw up the default firefox package in mint.
Is the avahi-daemon service running?
sudo systemctl status avahi-daemon
If not, start it:
sudo apt install avahi-daemon
sudo systemctl enable avahi-daemon
sudo systemctl start avahi-daemon
Is anything listed when you do:
sudo ufw status verbose
If so, you may have ufw blocking mDNS resolution. Then make sure you do this:
sudo ufw allow mdns
You may find this post to be of interest:
sudo nano /etc/systemd/resolved.conf
Change #MulticastDNS=no to MulticastDNS=yes
#Enable mdns for eth and wifi:
sudo systemd-resolve --set-mdns=yes --interface=wlp43s0
sudo systemd-resolve --set-mdns=yes --interface=enp45s0
If all else fails, maybe ‘just’ switch to Debian? I know for sure it works out of the box. We’ve had people with similar mysterious problems on Mint and sometimes Pop-OS (both based on Ubuntu). And Ubuntu itself definitely ships snaps by default so it seems these 3 distros are the worst when it comes to unexplained mDNS problems. It’s actually a wonder how they allow their OS to be broken out of the box with mDNS considering so many products rely on it.