(I'm having a problem with this site: I can't read the question text so I'm having to make initial suggestions based just on the title.)

Is it a plain page with "Access Denied" in large text, and another line with a Reference #? That is characteristic of a perimeter security system/Web Application Firewall designed to prevent bot and other suspicious connections to the website.

Some possible issues to consider:

(A) If you are using a VPN when accessing these sites, try without the VPN.

When you are using a VPN, your IP address is from a remote system used by many strangers. So if that IP address is temporarily banned due to someone else's activity, that also will affect you. If you need the VPN, try selecting a different server or exit node in your VPN software.

(B) If you have customized any privacy preferences that affect browser requests -- for example, modifying your "user agent" or referring site header -- you may need to undo those changes

Also, some add-ons may modify headers in a way that looks suspicious to these systems. We can't really tell how your browser identified itself to the problem site based on how it identified itself to this site, because add-ons are restricted in how they interact with this site. Can you think of any add-ons you use that might make privacy-related tweaks to your requests?

(C) If you have Firefox set not to accept ANY cookies, that also could be a problem for some sites

(D) Maybe your requests are modified by an intermediary (such as a proxy server, your security software, or an interloper)

Although most people are not intentionally using a proxy server, Firefox may discover one set up in your system settings. Sometimes forcing Firefox to ignore those settings helps with weird connection issues. Here's how:

Open the Settings page using either:

• "3-bar" menu button > Settings
• (menu bar) Tools > Settings
• type or paste about:preferences into the address bar and press Enter/Return to load it

In the very tiny search box at the top of the page, type proxy and Firefox should filter to the "Network Settings" section of the page.

Click the Settings button, change the top setting to "No Proxy" and then click the OK button at the bottom of the dialog to save your change.

Any difference?

Yes it is a plain page with "Access Denied" in large text and another line with a Reference #. Have tried or checked items A,C and D with no resolution. Have not tried item B as I do not know where to go to access user agent or referring site header. Please advise on that and any other suggestions would be helpful. Thanks for your advice and information. - Harry

Hi Harry, there probably are other sites for this, but I have a basic test page that lists back how your browser identifies itself:

https://www.jeffersonscher.com/res/jstest.php

The user agent string is shown in red (being in red doesn't indicate whether there is a problem).

Does yours look like:

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:106.0) Gecko/20100101 Firefox/106.0

Otherwise, do you recall changing any privacy-related settings, other than the standard Tracking Protection settings?

Sorry I took so long getting back to you. The user agent string is exactly as you have posted and is red. Don't recall changing any privacy-related settings. - Harry

Hmm, maybe it's something more basic. If a site is generally known to work in Firefox, these are standard suggestions to try when it stops working normally:

Double-check content blockers: Firefox's Tracking Protection feature, and extensions that counter ads and tracking, may break websites that embed third party content (meaning, from a secondary server).

(A) The shield icon toward the left end of the address bar usually turns a bit purplish when content is blocked. Click the icon to learn more or make an exception. See: Enhanced Tracking Protection in Firefox for desktop.

(B) Extensions such as Adblock Plus, Blur, Disconnect, DuckDuckGo Privacy Essentials, Ghostery, NoScript, Privacy Badger, uBlock Origin or uMatrix usually provide a toolbar button to manage blocked content in a page. There may or may not be a number on the icon indicating the number of blocked items; you sometimes need to click the button to see what's going on and test whether you need to make an exception for this site.

Cache and Cookies: When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Clear Firefox's Cache

See: How to clear the Firefox cache (only select Cached web content, don't clear all cookies and site data)

If you have a large hard drive, this might take a few minutes.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, click the lock icon at the left end of the address bar. After a moment, a "Clear Cookies and Site Data" button should appear at the bottom. Go ahead and click that. Firefox will ask you to confirm; go ahead and confirm.

Then try reloading the page. Does that help?

Testing in Firefox's Troubleshoot Mode: In this mode, Firefox temporarily deactivates extensions, hardware acceleration, any userChrome.css/userContent.css files, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is running:

You can restart Firefox in Troubleshoot Mode using either:

• "3-bar" menu button > Help > Troubleshoot Mode... (before Fx88: Restart with Add-ons Disabled)
• (menu bar) Help menu > Troubleshoot Mode... (before Fx88: Restart with Add-ons Disabled)

and OK the restart. A small dialog should appear. Click the Open button (before Fx88: "Start in Safe Mode" button).

If Firefox is not running:

Hold down the Shift key when starting Firefox. (On Mac, hold down the option/alt key instead of the Shift key.) A small dialog should appear. Click the Open button (before Fx88: "Start in Safe Mode" button).

Note: Don't use the Refresh without first reviewing this article to understand what will be deleted: Refresh Firefox - reset add-ons and settings.

Any improvement?

I cleared the sites cookies using the #2 directions under the cache and cookies, reloaded the page and that did the trick. Thank you so much for your patience and time spent walking me through this. It is always great to have someone who knows their way around the system to help with problems. Thanks again. - Harry