Found something interesting with a MG-90. Had a Telstra SIM and also an OPTUS SIM in slot A and found that it was being reset every 1.5-2 mins. Tried all sorts of things including updating to 4.0.5 and still had the issue.
Found that by disabling the default monitor on that interface did the trick and it now stays up.
Hope somebody finds this useful , back to evaluating.
If the default monitor could not be reached via either connection, then that is expected behavior of the MG90. We recommend always changing the default monitor to something “pingable” within your network that you can have some control over. Otherwise, you took the correct action by disabling the monitor while you continue with your configuration and testing.
Hope this helps.
I also have the same issue of the MG-90 Restarting my Cellular interface.
This ONLY occurs when the MTU Size is modified on the WAN Cellular Link from 1500 to 1400.
I need the ability to have a MTU size of 1400 to connect VPN over Cellular to Microsoft Azure VPN Gateway
Remove all monitors and still have same issues. Changing the MTU back to 1500 , the link stays up, but cannot connect to VPN
Any ideas ?