There is a note that tcp_set_src_addr() should be used only on init:
- https://github.com/kamailio/kamailio/blob/master/src/core/tcp_main.c#L217
Are you sure it does not have side effects, when there is a mix of forcing and not-forcing send socket?
Is it compatible with the old behaviour when the global parameters tcp_source_ipv4/tcp_source_ipv6 were supposed to be global for all traffic?