Hello,
To start, device configuration files indicate that the router had firmware updates from legacy firmware to current RutOS with Keep settings option enabled.
As a result, you have failover configured, though router's only WAN source is mobile, making failover unnecessary. It is also creating rules, which might cause LAN devices from having internet access.
In regards to WiFi interface being stopped, this is a known issue, which was resolved in 7.03.3 firmware release.
The best solution would be to update the router to 7.04.1 firmware version with Keep settings option disabled. This should return proper operation, but, be aware that you will loose current device configuration.
Best regards,