I’ve been testing out using RouterOS User Manager as a RADIUS server for a small network. It has been working fairly well, but I did run into one issue (twice) so far…

If you make a RADIUS request to a RADIUS server on its loopback address, the reply will come back from a completely different (interface) IP address, which no OS or client is expecting.

The solution is to use the interface IP, or not use a loopback at all. To make the RADIUS server a client of the network like any other device vs building it into routing.

This probably makes sense for a simple network.

This also reminds me a little bit of the SNMP Oddity I ran into about 10 years back.