OK, I’m confused.
This looks just like this other thread. He updated to 15 and 15.0.1 without improvement.
From an iOS perspective, you could try resetting the network settings. If it really is caching the wrong intermediate certificate, that might kick it out. Settings → General → Transfer or Reset iPhone → Reset, then select Reset Network Settings. Be prepared to re-join any WiFI networks if you do that.
I’m certain that iOS has trusted the ISRG Root X1 CA since iOS 10. Intermediates shouldn’t be cached by iOS, so as long as the current R3 intermediate is being sent by Plex, it should be trusted.
And in the second screenshot, the dates on the certificate itself look reasonable.
But the Expired date on the first screenshot is exactly, precisely, when the old Let’s Encrypt R3 intermediate expired. iOS enforces that the whole chain is valid, so I would expect iOS not to trust that.
This is the sort of error I would expect if a server was sending the old intermediate certificate chain.
@jmahaffey09, can you visit this on the iPhone? This page uses a certificate that was issued by the Let’s Encrypt R3 intermediate, just like Plex Media Server certificates.
@jmahaffey09, what did you cover in the screenshot? Is it a name like 01-02-03-04.abcdefghijklmnopqrstuvwxyz123456.plex.direct?
But that’s confusing. It doesn’t seem like that would fit in the space that was covered up.
If you’re willing to share, can you PM me your public IP address? I’d really like to see what the server is doing, just to confirm.
