Hi,
Normally, I would recommend you to check if your keyboard language is set right; if you don't have caps lock on; if you're using admin01 and not the WiFi password when logging in to WebUI..
But if you went through all these points, you can reset the router FULLY by going into bootloader menu and flashing firmware there:
https://wiki.teltonika-networks.com/view/Bootloader_menu
EB.
