Maintenance for the week of November 17:
• [COMPLETE] ESO Store and Account System for maintenance – November 17, 6:00AM EST (11:00 UTC) - 4:00PM EST (21:00 UTC)
• Xbox: NA and EU megaservers for maintenance – November 19, 4:00AM EST (9:00 UTC) - 12:00PM EST (17:00 UTC) https://forums.elderscrollsonline.com/en/discussion/685477
Check your settings in Firefox to see if one of them is causing an issue and if so, reset it to default. Also clear cache and cookies to see if that helps.