Hi…
DNS changing maybe help… who know?.. sorry my words… it is a " guess who " in the dark…
About DNS
look this … to change your DNS.
sample:
Google DNS server are: 8.8.8.8 and 8.8.4.4
Teltonika, also… have a new firmware for your device:
RUT901 Firmware Downloads - Teltonika Networks Wiki (dec/17/2024)
Are you using WAN Failover?
https://wiki.teltonika-networks.com/view/RUT901_Failover