Using a VPN with my full node.

I've been using XMR more and more recently, rather than bitcoin, for my spends and decided it was time to run my own node. This was a relatively simple process using a Lenovo microcomputer I had and by following the docker guide on sethforprivacy.com. The node has synchronised and I have connected a new wallet and everything works great remotely. I was however thinking of using a VPN before I started to use anything. I have a mullvad account downloaded an ovpn file using TCP/443 and followed mullvads guide to install it on my RT-AC88U (Merlin-asusWRT) and set it up killswitched for the nodes local IP. When I do this however I immediately lose remote connections. I thought perhaps this may be because the VPN was blocking the RPC port so I used mullvads port opening tool. Using the port number they provided, I then created a port forwarding rule, forwarding internal: 18089 to external: (port mullvad provided). And in my wallet settings used the mullvad port number and tested with my networks public IP and the VPNs public IP but that also failed.

Unfortunately this didn't work either. I'm a little lost when it comes to getting into the weeds with networking and have only a basic understanding. I could use tor but since my device already uses a VPN I'd prefer not to have keeping swapping it for orbot everytime I want to use my wallet, and I'd also prefer to tors instability.

I know this may be a difficult question to answer but the Monero community has been very welcoming to an ex bitcoiner so thought I'd ask incase someone has gone through this and knew how to do it or an easier way