[Freeswitch-users] NDLB-force-rport question

Hi! I’m having strange issues on registering phones behind NAT on FreeSwitch. Schema is Phone (port 5063)  -> Router (NAT) (port 1023) -> Freeswitch Phone registering from port 5063. NAT is changing this port to 1023. Freeswitch receiving register message from port 1023, but still replying to port, that listed in Contact Header. So, Router can’t route this request back correctly. NDLB-force-rport and aggressive-nat-detection is enabled on internal profile. What I got, this issue is when router changes port to 1024 or lower. If port is higher that 1024, than it’s working ok. Also this problem with UDP only, with TCP all is ok. Maybe I’m missing something in config? Thanks. Regards, Igor