If you're getting error saying "Failed to resolve hostname", it means something is wrong with the internet on your router.
- Check what WAN connection is set to main, if you're using a SIM card - select it as a main WAN connection and check if you don't need additional configurations for it. (APN, PPPoE etc..)
- Check if you can ping external networks from routers CLI, ping an address like 220.127.116.11
- Check if your computer has automatic network adapter settings and not static IP.