DNS Resolution Not Working

Turn off systemd-resolved

That is, with the OPT and A reversed.

Mint uses systemd-resolved and it seems plausible that your router is "special" or even plain buggy and that systemd-resolved refuses the reply. Clearly we have to compensate for things working for you from the other systems and the easiest test would be to disable systemd-resolved for a bit:

sudo systemctl disable systemd-resolved
sudo systemctl stop systemd-resolved
sudo rm /etc/resolv.conf

Then edit /etc/NetworkManager/NetworkManager.conf to insert "dns=default" in the [main] section and

sudo nano /etc/NetworkManager/NetworkManager.conf

You may have to recreate the /etc/resolv.conf with your nameserver.

sudo echo echo nameserver 10.169.212.1 > /etc/resolv.conf

Restart the Network Manager Service

sudo systemctl restart NetworkManager.service

or reboot. If things work for you then we can at least be certain it's (the combination of) systemd-resolved (and your router).

To re-enable systemd-resolved

Reenable systemd-resolved

sudo systemctl enable systemd-resolved
sudo systemctl start systemd-resolved

remove / comment out dns=default in the [main] section of /etc/NetworkManager/NetworkManager.conf 

Restart the Network Manager Service

sudo systemctl restart NetworkManager

This time however, rather than linking /etc/resolv.conf to /run/systemd/resolve/stub-resolv.conf, you provide that same content lacking only the options edns0 line:

sudo rm /etc/resolv.conf
echo nameserver 127.0.0.53 | sudo tee /etc/resolv.conf

If I'm not mistaken there should be no need to reboot to have the then current situation active but if I'm overlooking something feel free to. It is expected that things will now still work for you, i.e., with the only difference with the original situation the removal of options edns0. If I'm not mistaken you could in fact alternatively also restore the original link:

sudo rm /etc/resolv.conf
sudo ln -s ../run/systemd/resolve/stub-resolv.conf /etc/resolv.conf 

and set a global environment variable RES_OPTIONS= (i.e., empty) in for example /etc/profile (man resolv.conf) and reboot but that's untested.