Why can't I log in to Bank of America in Safari on iMac?

Starting +/- 2 to 3 months ago, logging in to Bank of America has become erratic. Probably 70% of the time it won't log in when using Safari (Version 18.4). Never was a problem before. However, no problem logging in when using Firefox.

When I can't log in using Safari, I sometimes get to the log-in page (70% of the time - ??), other times it never reaches that page and times out. When I do get to the log in page it tries to log in but get a message stating Safari can't find, can't connect with B/A's server.

Any ideas, suggestions how to correct this problem

[Re-Titled by Moderator]