Unable to login

I am having weird login issues. I have 3 computers - all the exact same model. 2 of them are windows 10 and one is windows 8.1 I can ONLY login to the cpanel on one of the windows 10 computers - I bought a new computer this past week and that one (win 10) is one of the ones that will not login. I have tried refreshing computer, browsers, uninstall, reinstall, clearing cache, changing internet ports, spoke with host forEVER as they can't find anything wrong on their end and I can switch internet cables to the one computer and it still logs in fine so pretty sure not ip. What settings do I need to look for??? I am stumped as the two windows 10 computers are set up the same and yet one of them works fine while the other one will not login. Appreciate any tips or direction of where to make changes in settings! THANKS!