unexpected behaviour on restore of wan link.

[MoonbeamFrame]

I'm currently running   OPNsense 20.7.5  though I don't think the following behaviour is version specific.

I've been trying to track down the cause of an inter PBX issue for a while and have been restarting my upstream WAN gateway as part of the testing.

What I was not expecting is that shortly after the WAN link is restored I see sessions between my LAN and other local interfaces drop e.g ssh sessions between LAN and DMZ.

Does anyone know if this is the expected behaviour and what the root cause may be?

Thanks