Why is the trunk not coming up in Asterisk?

Question

Asterisk

A trunk is configured from one asterisk to another via vpn. NAT is not used. The problem occurs when the light is turned off. After turning on, mikrotik starts first, then elastix. The trunk does not rise immediately, it rises in a day.
What they have already done and what they have come to:
- The trunk does not rise due to a timeout, the packets do not reach asterisk2
- On the second side they say that I am trying to connect from the outside, and not from the local area, and the firewall discards these packets
- But if I ping from Asterisk1 Asterisk2, and I look at tcpdump on the second side, the packets come from my locale
- If I try to raise the trunk, on the second side there are udp packets with an outgoing external address, of course they are discarded
A day passes and communication is restored. The connection is restored via vpn, everything is as it should be, packets from the external side of the first side no longer arrive on the second side.
Rebooting aschterisks, mikrotik, or just reconnecting vpn does not help.
How is this possible?)

Answer 1

Several options, most likely the asterisk is trying to raise the trunk, before raising the VPN on Mikrotik.
Explicitly disable such traffic in the Mikrotik firewall.
Most likely, in a day, the trunk rises due to the conaction-tracker of Mikrotik, obviously beat the connections from your asterisk with your hands.
also if you do not use NAT at all for sip traffic, then disable the /ip firewall service-port disable sip helper

Answer 2

It seems to me that once a day passes, then the DHCP lease may expire, along with which the route to the subnet can also be pushed. Try specifying a lease for 1 hour or less in the DHCP server settings and see if the connection is restored in this time. It's a long way. Faster - do dhclient ethX and see the routes in the system on server1.
In any case, you need to look at the routing and the reason for its inoperability at the time of the reboot.

Answer 3

add vpn networks to localnet
disable SIP-ALG on mikrotik-e(s)