client disregards configured port in some cases

[Synthetica9]

I have an attic server set up with a non-default https port, 4343 in my case. My config looks like this:

default-server = "myserver"

[servers.myserver]
endpoint = "https://myserver.mycompany.com:4343/"
token = "..."

If I then attic push to this, I get the following result after a timeout:

Error: error sending request for url (https://myserver.mycompany.com/_api/v1/get-missing-paths)

Caused by:
    0: client error (Connect)
    1: tcp connect error: Connection timed out (os error 110)
    2: Connection timed out (os error 110)

Somewhere along the way, the port number got discarded.

Paths that are uploaded internally in my network do download correctly.

Is this misconfiguration in my nginx reverse proxy? Bug in attic? A secret third thing?

[Synthetica9]

Ah, it came from a non-configured api-endpoint it seems, now it works.