I'm most of the way through moving from one server to another. Servers are more or less the same, newer one has a newer version of Plesk.
Everything has gone very smoothly BUT now I check on Safari or Chrome on IOS none of the sites running SSL are working. (I use Lets Encrypt).
I thought this might be a local problem but I just checked Analytics and Safari stats have gone off a cliff for my sites. Other browsers are working fine. I did see a message briefly along the lines of "unable to parse".
My initial thoughts were that it was a DNS caching issue. My TTLs were set quite high. I figured that even if the site was still up and running on the old server this might cause an issue with the SSL certificate. I've tried to clear the cache on the iPhone but this hasn't helped.
Am at something of a loss as to what to try next.