If you experience an authentication failure when trying to connect BrightPay to Modulr, it is recommended to reset your Modulr authentication. To reset the authentication, follow these steps: 

1. Open the pay by Modulr window. 

2. Click on the spanner icon located at the bottom right-hand side. 

3. Select the option to reset authentication and re-enter your credentials. 

Clearing your browser's cache and cookies can also help resolve authentication issues. After clearing, try to reset authentication and ensure that you manually enter your login details rather than relying on saved credentials. If the 'Reset Authentication' option is greyed out, ensure that you have followed these steps correctly and try again.