I’ve got a MAX Transit Duo set up to establish an IPSec site-to-site VPN. The VPN establishes just fine, and traffic will pass for hours. Over time (I haven’t observed a specific pattern yet) the IPSec tunnel will stop working. The rest of the device works fine - WiFi is still up, cellular links are up, outbound traffic from behind the device works.
Nothing I do seems to cause it to attempt to re-establish the IPSec tunnel. The “Status” shows “Connecting” with the spinning wheel, but the IPSec Event Log just shows that the tunnel disconnected. It doesn’t show any connection attempts or other activity. Monitoring inbound traffic at the VPN hub shows no traffic coming from the MAX.
If I edit the settings on the MAX and disable the VPN tunnel, apply settings, and then re-enable the VPN tunnel and apply settings, I immediately see the traffic hit the VPN hub and the tunnel comes back up. Until the next time it happens.
I do not believe this is an issue on the VPN hub (other tunnels stay up when this occurs, and no attempts are even seen hitting the hub) or anything relating to the cellular connectivity – since simply disabling/re-enabling the tunnel will cause it to come back up, I do not believe it’s related to the cellular links. They stay established all the time. I have tried two carriers as the primary link in case that was the issue, but it does not appear to make any difference. It seems like the IPSec process on the MAX just needs to be “kicked” to wake up again.