CRITICAL: bthConnect() returned -1

Hello,

I am trying to connect my Raspberry Pi 4 to our Sunny Boy but Bluetooth will not connect:

Connecting to 00:80:25:18:80:63 (1/15)
Connecting to 00:80:25:18:80:63 (2/15)
Connecting to 00:80:25:18:80:63 (3/15)
Connecting to 00:80:25:18:80:63 (4/15)
Connecting to 00:80:25:18:80:63 (5/15)
Connecting to 00:80:25:18:80:63 (6/15)
Connecting to 00:80:25:18:80:63 (7/15)
Connecting to 00:80:25:18:80:63 (8/15)
Connecting to 00:80:25:18:80:63 (9/15)
Connecting to 00:80:25:18:80:63 (10/15)
Connecting to 00:80:25:18:80:63 (11/15)
Connecting to 00:80:25:18:80:63 (12/15)
Connecting to 00:80:25:18:80:63 (13/15)
Connecting to 00:80:25:18:80:63 (14/15)
Connecting to 00:80:25:18:80:63 (15/15)
Sun Feb 27 11:04:15 2022: CRITICAL: bthConnect() returned -1
Sun Feb 27 11:04:15 2022: INFO: Done.

Anyone have any suggestions on what is going on? It doesn’t matter what password I use, it does not seem to get to the point of authentication.

See No bluetooth connection to SM Tripower - #2 by gjvnidunvbivnbijhgjg

This is before login, so password isn´t the problem here.