Trouble logging in after hosting migration

After recently migrating my customers website from Godaddy to AWS my clients can’t seem to log on to the back end of their website. I’ve confirmed that passwords are correct and I can log in as them from my computer.

I have been able to reproduce this problem trying to log in from my girl friends computer. After typing in username and password it simply stays on the log in screen with no password error message.

Has anyone experienced this problem, your help would be greatly appreciated!

Thanks