Mojave to Monterey: safe to update?

[pshufd]

What network problem?

Some websites won't load - they become unreachable by the web browser. They are visible using some network lookup tools though.

Happens with wired Ethernet or WiFi.

I just downgraded Big Sur to 11.5.2 on one of the systems as the problem showed up there late in 2021.

 

[jcscol]

Some websites won't load - they become unreachable by the web browser. They are visible using some network lookup tools though.

Happens with wired Ethernet or WiFi.

I just downgraded Big Sur to 11.5.2 on one of the systems as the problem showed up there late in 2021.

If you activate the Developer's Menu in Safari (Safari->Preferences->Advanced->Show Develop Menu) you can check for any errors when loading webpages by going to Safari->Develop->Show Javascript Console.

It may be that the problematic sites have mixed http and https content. Apple deems this as insecure, and so Safari won't load them (but doesn't tell you why, though there will be a message in the Javascript Console). This change happened around the timescale you noticed.

 

[pshufd]

If you activate the Developer's Menu in Safari (Safari->Preferences->Advanced->Show Develop Menu) you can check for any errors when loading webpages by going to Safari->Develop->Show Javascript Console.

It may be that the problematic sites have mixed http and https content. Apple deems this as insecure, and so Safari won't load them (but doesn't tell you why, though there will be a message in the Javascript Console). This change happened around the timescale you noticed.

This behavior is seen in Firefox, Safari, Brave, Chrome and Edge.

It's also seen Mail and Synergy.

If the change was to the networking layer, then that could explain it. But it wouldn't explain the problem with all of the major browsers.