I still battle issues with rport when using tcp. UDP seems fine but tcp will fail without enabling the router's (ubiquiti in the most recent case) sip alg. Enabling the alg causes other issues including removing t38 from the client.
I will grab some traces but curious how others typically handle this. I would also note that I do not use the sip/rtp_ext_ip setting for 'autonat'. I will test using shortly in the chance that it might help.