You are right, this is an inbound connection. details in attached PCAP. [haproxy-stuck.pcapng.gz](https://github.com/kamailio/kamailio/files/6083218/haproxy-stuck.pcapng.gz)
What is strange here 1. after packet `#2` must be `TCP/ACK` packet. This packet does not exist. We have a half-open TCP connection. 2. packet `#7` has RST flag (client want reset connection), `ACK` - flag (connection established now), Sequence number: 1361 - the client sent data in unseen packets (this not received). 3. And there no more packets from the client.