Issues

error=CA signature digest algorithm too weak:

Solution: upgrade server CA to use at least SHA256

Workaround:

client.conf

# to work around the cert too weak issue 
tls-cipher "DEFAULT:@SECLEVEL=0"

And from man 3 SSL_CTX_set_security_level:

Level 0

    Everything is permitted. This retains compatibility with previous versions of OpenSSL.

Level 1

    The security level corresponds to a minimum of 80 bits of security. Any parameters offering below 80 bits of security are excluded. As a result RSA, DSA and DH keys shorter than 1024 bits and ECC keys shorter than 160 bits are prohibited. All export cipher suites are prohibited since they all offer less than 80 bits of security. SSL version 2 is prohibited. Any cipher suite using MD5 for the MAC is also prohibited.

/sbin/resolvconf: 31: kill: Operation not permitted

Reason: openresolv: resolvconf fails if called from openvpn during system start with "kill: Operation not permitted"

Problematic script: /lib/resolvconf/libc.d/avahi-daemon

LZO compression is disabled on server but used on client.

Solution:

explicitly disable comp-lzo no on server.