I found a strange bug:

I currently pin two cids from one node to another one. The sending node is on master and the receiving node is on 0.4.23. One pin runs absolutly fine, the second one received some nodes and then stalled for several minutes - like the connection died.

I started a ping from the sending side to the receiving side, and instantly the second pin action continued as soon as the first ping got through.

Both nodes have public IPv4/6.