To run AxCrypt online, start it from the command line with the switch:
(Note the double dashes).
I sincerely doubt that disconnecting from the Internet would cause a password error. Please verify this by copying and pasting the password you know is correct, with and without Internet.
Finally, if you’d like further help, please send us a complete error report like this: https://www.axcrypt.net/blog/send-complete-error-report/ .