Thank you for your reply.
It was a painful lesson.
i have a setup where I sync my contacts over a Nextcloud server. Everything used to work fine but one of my Android devices stopped syncing. Please note that the server, my other android device and thunderbird client is continuing to syncing properly. How to fix? Thanks.
Part of the error I get from Davx5:
2019-04-16 10:35:50 2 [HttpClient] <-- HTTP FAILED: javax.net.ssl.SSLHandshakeException: javax.net.ssl.SSLProtocolException: SSL handshake aborted: ssl=0x5e210c78: Failure in SSL library, usually a protocol error error:14077410:SSL routines:SSL23_GET_SERVER_HELLO:sslv3 alert handshake failure (external/openssl/ssl/s23_clnt.c:744 0x5e2b2830:0x00000000)
Android version: 4.4.2 (KOT49H.I9190XXUCPK1)
Device: samsung GT-I9190 (serrano3g)
We have added Conscrypt to DAVx⁵ 2.5 to provide modern TLS ciphers for old Android versions (which is the reason why the connection can’t be established: your Android 4.4 device doesn’t provide the modern ciphers which are required by your server).
Can you confirm that DAVx⁵ 2.5.1 works for you?
Yes, the new version solved the handshake issue.