Can't install IPSEC VPN Certificate on iOS 17.4.1

I have been using an IPSEC VPN for at least 6 years, and have never had an issue installing or re-installing certs on the iPhone. Until now.

The cert I was using expires soon, so I deleted the cert on my phone and then created a new Cert for my Phone (on my VPN server).

When I install the new cert, it of course asks for the password. I paste in the password for the Cert (as I've always done), and iOS says 'The password for the certificate "Identity Certificate" is incorrect'.

By default I generate 20 character random cert passwords. I tried a cert with a 6 character password and it fails to install with the same error.

My (perhaps erroneous) conclusion is that installing IPSEC identity certs doesn't work on iOS 17.4.1.