See these threads, these two should get you where you want to go. You will likely need to build a “tunnel in a tunnel.” You will want Zerotier to get past your ISP’s CG-NATing and filtering (most home grade internet providers that I know of will NOT let you build a VPN directly, unless you have a business-tier line). Wireguard (over the internal Zerotier IP address) to route traffic and to prevent accidental IP leakage. If you were to rely on Zerotier ONLY, you will need to setup a persistent route in advanced configurations of your travel router, PLUS you might accidentally leak your IP if the persistent route gets flushed, and need to rely on custom scripts. So I STRONGLY recommend the tunnel in a tunnel approach here since it is much more reliable and supportable for 99% of people.