Domain name as dynamic DNS for passive mode

[RainOne]

Hey, I've been researching this scenario for a while and I can't find any direct solutions.

I have a sFTPGo instance running inside an Unraid machine, through their docker application, behind a NAT.
I, obviously, can only get external passive mode to work if I input my external ip address on the SFTPGO_FTPD__BINDINGS__0__FORCE_PASSIVE_IP setting on the docker - so far so good.

If I don't input anything, it detects the internal Docker IP address (which wouldn't work for my local network). If I input my local ip address on that machine, Passive works internally, but obviously not externally. If I input my external IP, it works externally - everything working as intended so far.

I read a support ticket that said that Dynamic Domain support would be added on 4.5.0, and it seems like that indeed it was. However, if I put a domain name on the SFTPGO_FTPD__BINDINGS__0__FORCE_PASSIVE_IP variable, the service just won't start - the log just tells me that the application errors out:

{"level":"error","time":"2023-10-01T18:12:16.981","sender":"service","message":"could not start FTP server: could not load settings: the provided passive IP "{DOMAIN_GOIES_HERE}" is not valid"}

The message is provided exactly as is (I obivously changed the domain name with {DOMAIN_GOIES_HERE}, but the slashes and " are there on the message.

Do I need a different setting to pass a domain name as the external IP? I can't seem to figure this one out.

[stanthewizzard]

Same issue and interested by a solution