No access to 3 random websites

Hi:

On only 3 of the very many, many websites that I interact with, I cannot connect. These are Ticketmaster, calendars.com, and my AT&T account. I spent a huge amount of time trying to figure this out with Ticketmaster and Calendars.com, and they suggested trying other browsers. By way of example, I tried Safari, Firefox, Chrome, Edge, and DuckDuckGo (examples attached for Calendars.com and Ticketmaster) to no avail.

I had only 1 application blocked in Radio Silence, and it is completely unrelated to these 3 websites.

At some point someone suggested I turn off Radio Silence, but that did not work either (still no access to the 3 websites):

I then went to Activity Monitor and typed in radiosilence, getting this:

Quitting Process Name https://radiosilenceapp.com did nothing, so I Force Quit it and got this:

The 3 websites were still blocked.

Again, nothing happens if I quit com.radiosilenceapp.client.NetworkExtension in Activity Monitor. However, if I "Force Quit" it will disappear after a short delay, then I lose internet access for a minute, then com.radiosilenceapp.client.NetworkExtension reappears again.

But here’s what made me think the com.radiosilenceapp.client.NetworkExtension process was the issue: access to all 3 problematic websites is normal for a short period of time after internet access reappears! However, if I delay for a short while, all 3 websites are once again blocked and the com.radiosilenceapp.client.NetworkExtensionprocess was back running again in Activity Monitor.

This made me think I was onto something. So I went to the Finder, threw away the Radio Silence app, emptied the trash, and restarted. Activity Monitor showed that all radiosilence processes were gone:

But the 3 websites are still blocked :(

I'm in way over my head here, since I don't understand computers. But if anyone smart can puzzle this out I would be very grateful!

Thank you!

PS