[asterisk-users] Client Asterisks can't connect when main Asterisk reboot

[Administrator TOOTAI]

Hi all,

we are running some Asteriks (version 13 on Debian Stretch) as VM/kvm in 
datacenter and have trunks with other Asterisk (v1.8 11 or 13) instances 
behind FW. Problem we face is that when we reboot the DC Asterisks, the 
trunks (SIP or IAX) become alive from DC Asterisks to clients ones but 
UNAVAILABLE the other way.

In clients logs we see

Registration for 'XXX at ourDCAsteriks' timed out, trying again (Attempt #5550)

or UNREACHABLE in case of no registration or IAX

Sometimes a restart from client Asterisks is enough (SIP or IAX reload 
has no effect) to recover the full trunk, but in most cases we have to 
reboot the client server :(

If we use a VPN (OpenVPN) between Asterisks, no problem.

What can be the problem ?

-- 
Daniel