OpenVPN – Unable to Accept Multiple Connections from Same User

Situation

• I'm using OpenVpn Server Access appliance, not the free CE edition; I do not know if they're different in config or in behaviours.
• Current appliance version is: 2.1.9
• Server version: 2.5.2
• License status: 2 devices
• All of the following configs are done using official web admin interface
• OS Ubuntu 18.04: Linux realtebo.example.com 4.4.0-134-generic #160-Ubuntu SMP Wed Aug 15 14:58:00 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

Configurations involed

• Multiple Sessions per User ON
• Listinening on eth0: 192.168.1.225
• Ports: tcp/1194, udp/1194
• OSI layer: 3 (routing/NAT)
• Server config directives contains only duplicate-cn
• Server config directives contains only duplicate-cn
• I saved, and confirmed to propagate configs to running
• I already tried to restart service, and also to reboot server; nothing changes

The problem

• Installed OpenVpn official app both on iPad and on an Android Phone
• Downloaded the client certificate.

• I opened the .ovpn file and I can see

   # Extra user-defined configuration
   duplicate-cn
  

• I connect to VPN using the iPad

• I connect to VPN using Android Phone
• iPad is being disconneted from VPN

• iPad expressly tellme

  Client was halted by server: disconnected due to new connection by same user.
  

Logs

Note the rows starting with OVPN 5 OUT

[-] OVPN 4 OUT: '192.168.1.1:55322 TLS: Initial packet from [AF_INET]192.168.1.1:55322, sid=ef370909 6ae63962'
[-] OVPN 4 OUT: '192.168.1.1:55322 VERIFY OK: depth=1, /CN=OpenVPN CA'
[-] OVPN 4 OUT: '192.168.1.1:55322 VERIFY OK: nsCertType=CLIENT'
[-] OVPN 4 OUT: '192.168.1.1:55322 VERIFY OK: depth=0, /CN=realtebo'
[-] OVPN 4 OUT: '192.168.1.1:55322 peer info: IV_GUI_VER=net.openvpn.connect.ios_3.0.0-712'
[-] OVPN 4 OUT: '192.168.1.1:55322 peer info: IV_VER=3.2'
[-] OVPN 4 OUT: '192.168.1.1:55322 peer info: IV_PLAT=ios'
[-] OVPN 4 OUT: '192.168.1.1:55322 peer info: IV_NCP=2'
[-] OVPN 4 OUT: '192.168.1.1:55322 peer info: IV_TCPNL=1'
[-] OVPN 4 OUT: '192.168.1.1:55322 peer info: IV_PROTO=2'
[-] OVPN 4 OUT: '192.168.1.1:55322 peer info: IV_LZO=1'
[-] OVPN 4 OUT: '192.168.1.1:55322 peer info: IV_LZO_SWAP=1'
[-] OVPN 4 OUT: '192.168.1.1:55322 peer info: IV_LZ4=1'
[-] OVPN 4 OUT: '192.168.1.1:55322 peer info: IV_LZ4v2=1'
[-] OVPN 4 OUT: '192.168.1.1:55322 peer info: IV_COMP_STUB=1'
[-] OVPN 4 OUT: '192.168.1.1:55322 peer info: IV_COMP_STUBv2=1'
[-] OVPN 4 OUT: '192.168.1.1:55322 peer info: IV_HWADDR=D3E089DB-77B9-4A5B-95AA-2081A4EB5366'
[-] OVPN 4 OUT: '192.168.1.1:55322 peer info: IV_BS64DL=1'
[-] OVPN 4 OUT: '192.168.1.1:55322 Control Channel: TLSv1.2, cipher TLSv1/SSLv3 ECDHE-RSA-AES256-GCM-SHA384, 2048 bit RSA'
[-] OVPN 4 OUT: '192.168.1.1:55322 [realtebo] Peer Connection Initiated with [AF_INET]192.168.1.1:55322'
[-] OVPN 5 OUT: 'MANAGEMENT: CMD \'client-kill 1 "HALT,disconnected due to new connection by same user"\''
[-] OVPN 5 OUT: 'Delayed exit in 5 seconds'
[-] OVPN 5 OUT: "SENT CONTROL [realtebo_AUTOLOGIN]: 'HALT,disconnected due to new connection by same user' (status=1)"
OMIClientAuth,0,] AUTH SUCCESS {'status': 0, 'reason': 'local auth succeeded', 'serial_list': [], 'user': u'realtebo', 
   'proplist': {u'prop_autologin': u'true', u'pvt_password_digest': '[redacted]', u'type': u'user_compile',
   u'prop_autogenerate': u'true'}, 'common_name': u'realtebo', 'serial': '4'} cli=u'ios'/u'3.2'
[-] OVPN 4 OUT: "MANAGEMENT: CMD 'client-auth 2 0'"
[-] OVPN 4 OUT: 'realtebo/192.168.1.1:55322 OPTIONS IMPORT: compression parms modified'
[-] OVPN 4 OUT: 'realtebo/192.168.1.1:55322 MULTI: Learn: 172.27.232.3 -> realtebo/192.168.1.1:55322'
[-] OVPN 4 OUT: 'realtebo/192.168.1.1:55322 MULTI: primary virtual IP for realtebo/192.168.1.1:55322: 172.27.232.3'
[-] OVPN 4 OUT: "realtebo/192.168.1.1:55322 SENT CONTROL [realtebo]: 'PUSH_REPLY,explicit-exit-notify,topology subnet,route-delay 5 30,
    dhcp-pre-release,dhcp-renew,dhcp-release,route-metric 101,ping 12,ping-restart 50,auth-tokenSESS_ID,comp-lzo yes,redirect-private 
    def1,redirect-private bypass-dhcp,redirect-private autolocal,route-gateway 172.27.232.1,route 192.168.1.0 255.255.255.0,
    route 172.27.224.0 255.255.240.0,dhcp-option DNS 192.168.1.228,dhcp-option ADAPTER_DOMAIN_SUFFIX homenet.telecomitalia.it,
    register-dns,block-ipv6,ifconfig 172.27.232.3 255.255.254.0,peer-id 0,cipher AES-256-GCM' (status=1)"
[-] OVPN 4 OUT: "realtebo/192.168.1.1:55322 Data Channel: using negotiated cipher 'AES-256-GCM'"
[-] OVPN 4 OUT: "realtebo/192.168.1.1:55322 Outgoing Data Channel: Cipher 'AES-256-GCM' initialized with 256 bit key"
[-] OVPN 4 OUT: "realtebo/192.168.1.1:55322 Incoming Data Channel: Cipher 'AES-256-GCM' initialized with 256 bit key"
[-] OVPN 5 OUT: 'realtebo_AUTOLOGIN/192.168.1.1:39835 SIGTERM[soft,delayed-exit] received, client-instance exiting'

Side notes

• The user is a standard one, _is not an admin _
• I've already tried to revoke certificate, delete user, recreate, reinstall certificate on both devices; nothing changes
• As from a comment, I am not using static IPs
• OpenVpn server is at latest available version, 2.5.2
• This issue seems to be fixed since v1.7.1
• while connecting 2 devices with the same user do not works, connecting 2 devices with different usernames works

Similar questions, and why them do not helped

• openvpn issue avoid simultaneous access: I've already the duplicate-cn option in my config