I seem to be able to connect with nc:

$ nc pizero.local 7624 -vz
nc -vz pizero.local 7624
nc: connectx to pizero.local port 7624 (tcp) failed: Connection refused
nc: connectx to pizero.local port 7624 (tcp) failed: Connection refused
Connection to pizero.local port 7624 [tcp/indi] succeeded!

As you can see, the connection is first refused twice and succeeds the third time.
If I try to connect from software, the connection gets refused (TCP error 61).

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