I have two servers (and different other machines) on two different LANs joined by a wireguard tunnel between the routers, with DynDNS running on both, and wireguard on all mobile devices that need access to the LAN.
If your router can natively run wireguard, I'd highly recommended. It just works. Or just use tailscale, it's wireguard for lazy people
Set up VPN = scan QR code. Love how easy everything has gotten