Thank you for reaching us.
How is everything connected ?
Could you draw a topology with IP addresses and ports being used?
Could you check in Windows setting , adapter settings if its on DHCP or static IP. If its on static is it configured with proper IP address, subnet mask and default gateway . Also have you tried to set the correct DNS server manually if its on auto.
Could you share the configurations screenshot of the Teltonika and non Teltonika router and PC adapter settings.
Make sure the said device is not blacklisted in the router .