Safari not connecting to a website

[Grandmaw]

I have used my library's website for a long time to reserve and renew books. Suddenly last week, Safari will not log in. I get a message saying" Safari cannot open page because it could not establish a secure connection to the server". Any suggestions as to how to remedy this, please

That probably means it is objecting to the library's security certificate - something you don't see but which the web browser uses to check it is talking to the correct site. Reports suggest that Safari is fussier than other browsers about this and does sometimes prevent access to valid sites. Most other browsers at least give you the chance to ignore the problem and go into the site anyway.

It is worth checking that the date and time on your device are set correctly. If these are wrong that could cause the problem. If they are correct I would suggest trying a different browser such as Firefox or Chrome, both of which are free.

Thank you for your reply. The odd thing is that I can log on to the library site from my phone and the browser is the same as on my ipad - Google.
Also, this has only just started to happen- I have used the library website on my ipad for a few years without a problem until last week.
I tried logging into the site on a friends ipad and was able to do it!