User login errors but is using the correct info, I can log into their account fine.

I have a strange situation where a new client cannot log into their account in WHMCS with the correct user/pass. I can log into their account using their user/pass from any computer I choose. However, I have done a Zoom session with them where I controlled their computer remotely, entered in the info exactly the same way, but it says the login is invalid. Tried it with both Chrome and Edge.

Even after doing a password reset from their remote computer and using the new login info it still says invalid password but only when done from their machine. If I do it on mine (even using a different browser) it logs in fine.

Any idea what might be causing this problem? A firewall issue would block them from seeing anything at all on the site so I am guessing that can't be it?