Hi@Subhadipkundu,

Thank you for reporting your issue to our community.

If you're struggling to access your router's login with the right credentials, consider these scenarios for resolving the issue: 
Scenario One: Unable to log in to the Web Interface or the Tether App with the correct login password.
    1). Reboot the router. 
    2). Try different browsers and incognito mode. 
    3). Try different devices. 
    4). Hard reset the router to create a new password or log in with the default admin. 
Scenario Two: Able to log in through the Web Interface but not the Tether App, or vice versa.
   1). Update the router's firmware. 
    Via Web Interface: Go to Advanced > Advanced > System Tools > Firmware Upgrade to check for updates.
    Via Tether App: Tap Tools > System > Firmware Update. 
    2). Update your Tether app to the latest version.
    3). Reboot the router. 
    4). Try different devices.
    5).  Hard reset the router. 
Note: A hard reset will revert the router to its factory settings without Internet access, requiring reconfiguration.