This is the RUT955 setup:
1. Firmware version: RUT9XX_R_00.06.06.1
2. Internet connectivity is using mobile only on a single Sim card with roaming activated.
The internet connection was stable for several days but suddenly lost connection.
Checks done: No change in physical connections etc.
From the event logs:
1035|1631796316|Mobile Data|Mobile data disconnected
1036|1631796328|Mobile Data|Mobile data connected: SingTel
1038|1631846769|Mobile Data|Mobile data connected, IP: XX.XXX.XX.XXX SingTel
1. At 1631796316, the mobile data connection was lost
2. At 1631796328, the mobile data was supposedly connected but without an IP. From this time onwards there was no connection until it was rebooted at 1631846769.
3. After the reboot at 1631846769, the mobile data connection was established with an IP and there was Internet connectivity.
I have the troubleshooting logs and can send it to you for further analysis.