How to change the src port when operating the src-nat or masquerade on a Mikrotik?

Configured telephony.
Asterisk (LAN) -> Mikrotik -> (WAN) -> Server
SIP messages normally reach the server and the asterisk.
Using SDP to asterisk and specify the server ports for video, for example the asterisk as src port specifies 11096, server - 55078.
The server first sends the RTP and they normally come to the asterisk, but when asterisk sends RTP to the server, the router changes the src-port 11096 1024, respectively, the server does not accept these RTP because the port is not the same.
In masquerade NAT configured
July 9th 19 at 13:37
4 answers
July 9th 19 at 13:39
Normal Softswitch always ready RTP halt with another Polta for clients behind NAT
If your can not try to use STUN
for asterisk 11 and above
sip.conf [general]
icesupport = yes
rtp.conf
stunaddr=sip.stun.tld
July 9th 19 at 13:41
try dst-nat... with this hardship...
July 9th 19 at 13:43
This is the principle of operation of NAPT https://ru.wikipedia.org/wiki/NAT
I don't think you can as it is trivial to manually specify the mapping with overloaded NAT.
I think in your case it is easier to configure a VPN tunnel from Server to Mikrotik.
July 9th 19 at 13:45
Suddenly helped add a rule with action=netmap dst-nat

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