henningw left a comment (kamailio/kamailio#4238)
Its strange that you are seeing TCP operations in your backtrace, when you are saying that no TCP was configured for this node. Can you share the listen cfg?
Regarding the Kamailio 5.7.4 - its an old version which is not maintained anymore from the open source project. I would suggest to update to a maintained version, e.g. one of the latest 5.8.x or 6.0.x versions.