Hi everybody,
This is my first mikrotik product and I hope you can help me solve some very strange issue.

recently my ATL LTE18 kit, running 7.8 Stable started to randomly lose connection to other LAN devices. It become unresponsive. It will not provide any IP to connected devices and often won’t respond to PING. Even direct connection to it doesn’t change anything. After restart no errors or messages are left in the logs, since they are saved to memory and the device has no apparent ability to store logs in some permanent way. I did caught some warnings informing of inability to assign IP to connected devices once, when I managed to connect to it for a couple of seconds before the device disconnected again.

Device is plugged into Ubiquiti POE switch US-8-60W.
Issue is most prominent when users attempt to run for eg. online games on the network, or watch netflix.
All devices used to be configured to obtain IP from Mikrotik via DHCP, I changed it during testing and assigned static IP to every AP and switch. Other devices that I’ve assigned static IPs to can be PINGed even when Mikrotik is down and unresponsive.

Things I tried:
1. Use different SIM card
2. Change power source (POE switch -> Mikrotik POE adapter)
3. Direct connection to router
4. Restarting the device - works till it errors again
5. Reset to factory settings - Same thing as above
6. DHCP lease set to 30 days
7. System upgrade to 7.8
8. System upgrade to 7.9rc2
9. Set static IP for every important device in network (they all respond to PING except the Router)
10. Connection via cable/wi-fi, both via browser and winbox

I'm experiencing something like this on a brand new ATLGM&EG18-EA.
I'm on 7.9 but after a while connected via winbox, it wasn't possible to connect anymore until I reset the device. And I hed to repeat this some times.
After reconfiguring it's working as a gateway, DHCP is working, but there is no way to connect via winbox or webfig.
This is happening even if I disable all firewall rules. Any suggestion?

I'm also experiencing something like this on a brand new ATLGM&EG18-EA running 7.15 beta9.
I've also reverted back to the stable release but the problem is still there.

It happens randomly: sometimes it happens with no apparent reasons after hours, but I noticed that it mostly happens during configuration sessions.
I actived a watchdog that reboots the device if ping to the POE main switch is lost to mitigate it, but I really don't like it.
It seems also that LTE link stays up and running, obviously unusable by devices on network.

Any clue ?