OpenVPN certificate verify error in Red Hat Enterprise Linux 7

Issue

• A user has a problem with setting up an openvpn connection with a MD5 signed certificate. I already tried to add the following line to /usr/lib/systemd/system/NetworkManager.service: Environment="OPENSSL_ENABLE_MD5_VERIFY=1 NSS_HASH_ALG_SUPPORT=+MD5" but this does not solve the error, also not after a reboot.
• The following errors are reported when trying to establish openvpn connection:

Mon Jan 16 15:59:49 2017 us=187582 Data Channel MTU parms [ L:1576 D:1450 EF:44 EB:143 ET:32 EL:3 AF:3/1 ]
Mon Jan 16 15:59:49 2017 us=187635 Local Options String: 'V4,dev-type tap,link-mtu 1576,tun-mtu 1532,proto TCPv4_CLIENT,comp-lzo,cipher BF-CBC,auth SHA1,keysize 128,key-method 2,tls-client'
Mon Jan 16 15:59:49 2017 us=187646 Expected Remote Options String: 'V4,dev-type tap,link-mtu 1576,tun-mtu 1532,proto TCPv4_SERVER,comp-lzo,cipher BF-CBC,auth SHA1,keysize 128,key-method 2,tls-server'
Mon Jan 16 15:59:49 2017 us=187662 Local Options hash (VER=V4): '34fdf001'
Mon Jan 16 15:59:49 2017 us=187675 Expected Remote Options hash (VER=V4): '3e7d1066'
Mon Jan 16 15:59:49 2017 us=187689 Attempting to establish TCP connection with [AF_INET]10.10.10.20:80 [nonblock]
Mon Jan 16 15:59:50 2017 us=187841 TCP connection established with [AF_INET]10.10.10.20:80
Mon Jan 16 15:59:50 2017 us=187910 TCPv4_CLIENT link local: [undef]
Mon Jan 16 15:59:50 2017 us=187921 TCPv4_CLIENT link remote: [AF_INET]10.10.10.20:80
Mon Jan 16 15:59:50 2017 us=224005 TLS: Initial packet from [AF_INET]10.10.10.20:80, sid=dc51c6f6 c3be5add
Mon Jan 16 15:59:50 2017 us=837302 VERIFY OK: depth=4, CN=Example Root CA, O=Example, OU=Foo Bar, C=US, ST=New York, L=New York
Mon Jan 16 15:59:50 2017 us=837385 VERIFY ERROR: depth=3, error=certificate signature failure: CN=Example Root CA, O=Example, OU=Foo Bar
Mon Jan 16 15:59:50 2017 us=837435 OpenSSL: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed
Mon Jan 16 15:59:50 2017 us=837448 TLS_ERROR: BIO read tls_read_plaintext error
Mon Jan 16 15:59:50 2017 us=837456 TLS Error: TLS object -> incoming plaintext read error
Mon Jan 16 15:59:50 2017 us=837461 TLS Error: TLS handshake failed
Mon Jan 16 15:59:50 2017 us=837500 Fatal TLS error (check_tls_errors_co), restarting
Mon Jan 16 15:59:50 2017 us=837522 TCP/UDP: Closing socket
Mon Jan 16 15:59:50 2017 us=837580 SIGUSR1[soft,tls-error] received, process restarting
Mon Jan 16 15:59:50 2017 us=837613 Restart pause, 5 second(s)