Please explain the problem in detail. What happens? What is/are the exact error message(s) ?

Make sure you are not blocking content.

https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop also see https://blog.mozilla.org/security/2021/03/23/introducing-smartblock/

https://support.mozilla.org/en-US/kb/smartblock-enhanced-tracking-protection

Diagnose Firefox issues using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

Many site issues can be caused by corrupt cookies or cache.

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

• Delete cookies to remove the information websites have stored on your computer {web link}

• How to clear the Firefox cache {web link}

There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connection certificates and send their own.

https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites

https://support.mozilla.org/en-US/kb/secure-connection-failed-firefox-did-not-connect

https://support.mozilla.org/en-US/kb/websites-dont-load-troubleshoot-and-fix-errors

What do the security warning codes mean

Hi There,

When I try and open this website https://www.appserv.com/ess/ I can do so on my desktop in the office, but not on any other device outside the office. My Desktop is Windows based and my laptop and phone are both apple.

Is this enough info?

Thanks, Nick

On one browser, I get; https://www.appserv.com/ess/ Secure Connection Failed

The connection to www.appserv.com was interrupted while the page was loading.

The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
Please contact the website owners to inform them of this problem.

+++++++++++++++++++++++++++++++++++++++++++++++++++ On another, I get; Secure Connection Failed

An error occurred during a connection to www.appserv.com. PR_END_OF_FILE_ERROR

Web search: https://www.bing.com/search?q=pr_end_of_file_error

radi.stoyanov said Turns out the option DNS over HTTPS is what caused the problem.

jamesafuf123 said https://support.mozilla.org/en-US/questions/1264659#answer-1237475 my ISP was blocking sites like that

cor-el said This usually means that Firefox wasn't able to find a cipher suites to use to connect to this server and reached the end of the list. There can be two possibilities: one is that the server is outdated and doesn't support modern cipher suites, another might be that the server only supports a few cipher suites and Firefox doesn't support any of these.

You can check your browser and possibly compare this with the server setup. https://www.ssllabs.com/ssltest/viewMyClient.html

Thanks for the feedback, it still doesn’t explain why I would be able to open it in Firefox on my desktop in the office?

Different protection software/settings. Were you able to get access to your site?

Nope still doesn’t work

Please explain the problem in detail. What happens? What is/are the exact error message(s) ?

Please see image attached, I can log onto this page at my desktop at the office, but not outside the office and on any other device.

That is a website message. Contact their support.