Today, one of Let's Encrypt's chain-of-trust certificates expired. This
caused some of my older Apple devices to give a certificate warning when
trying to access some web sites.
The fix is simple: you just need to add the new Let's Encrypt certificate to
the certificate trust store in iOS. The new certificate that you need to add
is called ISRG Root X1. You can get the PEM file here:
https://letsencrypt.org/certs/isrgrootx1.pem
If your machine can't access the Let's Encrypt web site because it doesn't
support newer versions of TLS, then you need to download the PEM file on a
newer computer, then put it on a web server that supports plain HTTP or an
older TLS version, and download from there. I'm sure most people reading
this newsgroup know how to set up a local web server at home to do this.
--
]DF$
The New Apple II User's Guide:
https://macgui.com/newa2guide/