Since updating the OS on my MacBook Pro to Monterey and to 15.2 on the iPad, I find that some websites previously visited and known, can't be accessed due to being titled "Not Secure". Is there a setting to override this?
The 'Not Secure' label is normally an indication that you are accessing the site over HTTP instead of HTTPS – i.e. that your connection to the web server is not encrypted, and that you have no assurance that it is not being intercepted or otherwise messed with.
When this is the case, it is just a warning, however; it does not prevent access to the site. Here is an example, which I can access (with the 'Not Secure' warning) both on Monterey and iPadOS 15.2.
The fact that Safari is actually preventing access to your sites implies that there is something more seriously wrong with them – I would guess that you are in fact accessing them via https:// URLs, and they are being blocked because they are presenting invalid certificates (e.g. they are expired, were issued for a different site, or have not been signed by an authority that is trusted by your browser). But checking using the sites with deliberately broken certificates linked from badssl.com, none of those cases are presented with the 'Not Secure' label. Instead they display a scarier full-page 'This Connection Is Not Private' warning that explains what is wrong with the site.
Do you have an example of one of your problematic sites?
It does indeed show the 'Not Secure' label (indicating that the connection to the server is not encrypted) but it also displays the '404 Not Found' error page that is returned by the server.
To be clear, this has nothing to do with the operating system updates, and my computer is not preventing access to the site. There is simply no longer a web page at that address.
It appears that the Internet Archive's Wayback Machine crawled that page on 29 November, so it has only recently been taken down. The archived snapshot is here:
Very interesting Andrew thanks. Safari also shows for me the '404 Not Found' error page. I didn't know the page had been taken down. On looking at the link you gave on the Archive's Wayback Machine I see an early version of the page. Since then it was updated to include some of my photos. I know the owner and will discuss the situation in the New Year. Many thanks for your information.
Roy Rainford 