Hello @mirishall ,

Thanks for contacting our community.

For your case,please try the following steps:

1. Ensure your phone is connected to the main Wi-Fi network of your TP-Link device, not the guest network or any other network.
2. Update your router's firmware to the latest version by logging in to the TP-Link web management interface (http://tplinkwifi.net) and checking for updates.
3. Turn off any VPN application on your phone, as VPNs can interfere with local network communication.
4. Disable mobile/cellular data on your phone while using the Tether app to avoid connection conflicts.
5. Reboot your TP-Link router to refresh its connection and settings.
6. Close the Tether app completely (remove it from the background), then reopen it and try logging in again.
7. For iOS devices, enable "Local Network Access" permission for the Tether app (go to Settings > Tether App > enable Local Network Access).
8. Make sure no other devices are accessing the router's management page at the same time.