Are you really sure it's computer model (hardware) related issue?
Have you tried openvpn?
I don't know about mullvad, but I use a free proton vpn, downloaded a server
config (udp) and connect via openvpn command:
sudo openvpn servercfg.ovpn
Unfortunately I couldn't set it up with network manager. The VPN connects,
but does not resolve webpages. But through the terminal it runs ok. I made
myself a little script to start and stop it and placed an icon on desktop, so
I don't have open a terminal to start vpn every time.
