Retransmit issue

Looks like the server is unwilling to respond after the initial three way handshake, or the packets do not make it through at all. If I am not mistaken you have a RTT of about 5ms, and the retransmissions come after a couple of hundred ms, so they're not just out of orders etc. From the timing I guess you're capturing on (or very close to) the client, so what you might do to solve this issue would be to capture close at the server instead. If you test again you can tell if the packets all make it through to the server.

My bet is that you have some kind of MTU problem, because the small SYN-SYN/ACK-ACK packets get through fine and fast, but the larger request packets after them do not. So that would be another thing you can do: find out if there's a MTU less than 1500 between client and server, because the client network and the server network DO have an MTU of 1500 (deducted from the MSS of 1460 in the SYN-SYN/ACK packets). Maybe there is one connection that has an MTU of 576 (which would be the minimum MTU allowed for IPv4) somewhere in the middle, which would block your 604 byte packets.