Access Denied error message on several sites

No vpn

Kind of a dumb question, but when you said "switch off the Cox Wifi" did you mean your Wi-Fi in general or were you specially connecting to "Cox Wifi" the hotspot?

I disable wifi in my phone's Internet settings so that it would connect to the Google Fi 5G network. I've not been to another location with a different wifi network so I determine if I have the same issues. 

I just used Avast to scan the Cox Panasonic router/modem, but no malware was found. 

Do you have Advanced Security enabled by any chance? Also, when did this start happening? Since getting service or a new gateway or something more recent? Last, do all the errors mention the HTTP version of the site?

Sorry for all the questions but this is a tricky one.

It's a tricky problem indeed. The sites where I get the message are ones I use frequently and the problem seems to progressively get worse. On the Holland America site for example I start having problems after using the site for a while and then I started getting the access denied message when going to the site. But sites like Amazon work just fine. 

The only recent change I made was to add a range extender, but I removed that a few days ago and the problem did not go away

Yes, oddly all the error messages refer to "http" even though the link is https. I get the error whether I use a bookmark or search result link. 

Advanced Security is not enabled. Since enabling it allows one to manual grant access to sites, is this a potential option to try? 

BTW have tried restarting the Panasonic modem/router several times.  

https://drive.google.com/file/d/1bTMWbrEbNUsnmAKdpLjHo5i84vmtRs67/view?usp=sharing

Here is a screen shot of the error message. 

There's a video on this page that suggests a few possible fixes.  The 1st one, regarding proxy settings I think is most worth checking out.

answers.microsoft.com/.../8b151f8e-fff8-437c-8a93-7dc107f09115

Thanks very much for the suggestions, but these did not seem to solve the issue that appears to be something with my router/modem unit. If I connect to a different network I don't have the issue so it seems to be something in the Cox network. 

That probably means your IP address was blocked by those websites. The question is why. If it happens again I would do a scan with Malwarebytes on every device on the network. Also, try contacting one of the sites and see why they blocked you.

So changing the Panasonic Gateway only worked for a while and I was back to getting access denied messages on several sites. I also noticed my speed was not near what I was supposed to be getting so arranged to a technician to come. He replace the cable from my house to the street distribution box and suddenly everything started working just fine. That was about a week and a half ago and everything is still working. 

Sounds like your good to go! If you run into issues, let us know!