i own 4 RUT200 and one RUT951. The configuration work well in the beginning, but when i define fix IP adresses, the some routers crash. I can only make a factory reset to have access. And the game begins new. Without doing this, it seems no problem.
As Mike suggests, it would be wise to try re-flashing the firmware. This can be done via the use of the Bootloader menu. The guide for the process can be found here: Bootloader menu - Teltonika Networks Wiki
Could you also please elaborate on this part?
Where are you defining these IP addresses, and what are you setting them to? Could you post some screenshots? If these IPs are Public, please blur them out, as well as any serial numbers, mac addresses and such.