I set up Bunsenlabs on both of my elderly parents computers and then basically automated login stuff to the sites they use, pinned those tabs. Blocked all ads and trackers. Set Firefox to auto open on boot. Basically made them a Linux version of a chrome book where everything they need is in the browser and already active, no mudding around.
8 months later zero complaints from either of them.
You'll find that with any major VPN. The IP addresses they use to proxy your traffic eventually get flagged and blocked by lots of major players. Which is why VPN companies cycle through them quite often. As others have said, you'll either need to switch servers (and thus ips) or figure out another path.
I don't use mull but most have a way to exclude a given url or site from the tunnel if you need it. i.e. the site will work for you but it's coming from your own IP and unencrypted.