When HamWAN routing fails, it's useful to have a secondary communication channel into the network. This is called out-of-band (or OOB for short) communication. HamWAN doesn't pass regular network traffic over OOB links, only control information (eg: SSH) is allowed in most cases.
/ip route vrf add routing-mark=OOB interfaces=<OOB interface>
/ip address add interface=<OOB interface> address=<OOB IP>
/ip route add routing-mark=OOB gateway=<OOB default gateway>
/ip firewall mangle add chain=output action=mark-routing new-routing-mark=OOB src-address=<OOB IP>