RDM not resolving localhost

I have a situation where I connect to customer sites using AnyDesk making use of its TCP tunnelling feature (it is tons more stable than their big name VPN). The TCP tunnelling allows mapping a local port to a remote host port, then locally I connect to localhost and a custom port number. The custom port number isn't a requirement, but I have created a register of customer servers I connect to and assigned a unique local port number so that I can connect to multiple sites at the same time, i.e., instead of mapping 3389 on the remote host to 3389 locally I map local ports in the range of 10000-11000 to 3389 for the different servers.

This has all been working great until either of Mac OS 27 or the new RDM Mac version (2026.3.0.5) where now RDM is stating Unable to connect to host localhost, however a test connection to the same is working fine and the backup RDP tool (Windows app for just in case) is connecting just fine.