Chrome v Firefox in Rpi OS Bullseye

For a long time I used only Chrome as browser with Rpi OS. Then recently I found that it would not load my webmail inbox page. Plusnet suggested using Firefox ESR instead, and that worked. However when I click on Today’s Theorem on https://www.theoremoftheday.org/ I find that Firefox ESR does not work but Chrome does. Chrome and Firefox ESR appear so similar in so many respects that such a difference in behaviour comes as a shock. Can anybody suggest a reason for it?

https://www.theoremoftheday.org/

Looking at it in bog basic Windows Firefox:
The actual link code is to the HTTP URL which does a few attempts on redirects before settling on a successful HTTPS access

Various browsers are getting fussy about mixed HTTP and particularly plain HTTP called from HTTPS like this instance.

Ideally, the site authors will change the links in their front page to be HTTPS links.

Thanks. That seems a likely scenario.

I have been with PlusNet for two decades at least, and my personal website is all http. I cannot remember anything from PlusNet about changing private websites to https. Should I be making enquiries?

about changing private websites to https. Should I be making enquiries?

Yes.

about changing private websites to https. Should I be making enquiries?

No harm in making enquiries. But, if you really mean private, then quite likely, there is no real reason to change.

We are getting closer to the time when all browsers will expect to connect via https, and will flag all http-only sites as insecure. That’s pretty much the only reason to change.

The other side of the coin is that it’s easy to change. I changed my site a few years back to https-only. My hosting provider takes care of certificate renewal automatically, which is a neat solution to the only nuisance I can think of. Certificates are of course free of charge from Let’s Encrypt.

all browsers will expect to connect via https

Not existing ones. Many of us do not allow automatic updates.

The other side of the coin is that it?s easy to change

not necessarily. My private hosting is provided by RISC OS 5.28

I have been with PlusNet for two decades at least, and my personal website is all http.

PlusNet do offer secure, https, access to user webspace. I use it.