Now it works!!! Does anyone have this problem or know why it happens ... should I expect it to happen again.

BTW: I loaded Firefox 56.0 today ... will this have anything to do with the problem I experienced?

Sometimes what happens is the site is down for whatever. Or there are too many users already there.

Please flag your last post as Solved Problem so others will know.

At 8:00 AM on a Sunday morning I don't think a major bank's site would be very "busy"! The site could be down but ...

Does anyone else have another answer/solution?

"Server not found" indicates that Firefox did a lookup of the IP address of the server and did not find it. This can be caused by a problem at your service provider, or the site being in the midst of a change, or a problem in Firefox, or a problem with an intermediary, such as a proxy server or private VPN.

The main thing that comes to mind to check on the source of the problem is:

If you see this again, try the same address in another browser, such as Safari. If Safari can find a server address but not Firefox, there may be some odd difference between how they are looking up the site's IP address.

Checked using Safari ... similar story! But then it opened. Used that URL with Firefox and it now seems to be working. Thanks but keeping fingers crossed.

The site works for me as well, so I will mark your above reply as the solution. If you want to reopen then click Undo next to this marked reply.

Note that you can try these steps in case of issues with web pages:

You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.

• hold down the Shift key and left-click the Reload button
• press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• press "Command + Shift + R" (Mac)

Clear the cache and remove the cookies from websites that cause problems via the "3-bar" Firefox menu button (Options/Preferences).

"Clear the cache":

• Preferences -> Advanced -> Network -> Cached Web Content: "Clear Now"

"Remove the cookies" from websites that cause problems.

• Preferences -> Privacy -> "Use custom settings for history" -> Cookies: "Show Cookies"

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Appearance
• do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

As a last resort you can use "Forget About This Site".

You can remove all data stored in Firefox from a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History -> Show All History" or "View -> Sidebar -> History").

Using "Forget About This Site" will remove all data stored in Firefox from that domain like bookmarks and history and cookies and passwords and cache and exceptions, so be cautious. If you have a password or other data from that domain that you do not want to lose then make sure to backup this data or make a note.

You can't recover from this 'forget' unless you have a backup of involved files.

If you revisit a 'forgotten' website then data from that website will be saved once again.

• https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox