OpenVPN Server doesn't work when IPv6 is enabled... ever

[gjf]

Just to let everybody know what I've found.
The latest Merlin firmware doesn't allow to have OpenVPN server together with enabled IPv6 (I have tested with "native" setting).
In this case when connecting the client shows the following errors:

Spoiler: Errors log

Wed May 31 18:20:54 2017 env_block: add PATH=C:\WINDOWS\System32;C:\WINDOWS;C:\WINDOWS\System32\Wbem
Wed May 31 18:20:54 2017 env_block: add PATH=C:\WINDOWS\System32;C:\WINDOWS;C:\WINDOWS\System32\Wbem
Wed May 31 18:20:54 2017 env_block: add PATH=C:\WINDOWS\System32;C:\WINDOWS;C:\WINDOWS\System32\Wbem
Wed May 31 18:20:54 2017 env_block: add PATH=C:\WINDOWS\System32;C:\WINDOWS;C:\WINDOWS\System32\Wbem
Wed May 31 18:20:54 2017 env_block: add PATH=C:\WINDOWS\System32;C:\WINDOWS;C:\WINDOWS\System32\Wbem
Wed May 31 18:20:55 2017 NOTE: Release of DHCP-assigned IP address lease on TAP-Windows adapter failed (code=1228)
Wed May 31 18:20:55 2017 SIGHUP[hard,] received, process restarting
Wed May 31 18:20:55 2017 OpenVPN 2.4.2 x86_64-w64-mingw32 [SSL (OpenSSL)] [LZO] [LZ4] [PKCS11] [AEAD] built on May 11 2017
Wed May 31 18:20:55 2017 Windows version 6.2 (Windows 8 or greater) 64bit
Wed May 31 18:20:55 2017 library versions: OpenSSL 1.0.2k 26 Jan 2017, LZO 2.10
Wed May 31 18:21:01 2017 WARNING: --ns-cert-type is DEPRECATED. Use --remote-cert-tls instead.
Wed May 31 18:21:01 2017 TCP/UDP: Preserving recently used remote address: [AF_INET]xxx.xxx.xxx.xxx:1194
Wed May 31 18:21:01 2017 UDP link local: (not bound)
Wed May 31 18:21:01 2017 UDP link remote: [AF_INET]xxx.xxx.xxx.xxx:1194
Wed May 31 18:21:01 2017 [Server] Peer Connection Initiated with [AF_INET]xxx.xxx.xxx.xxx:1194
Wed May 31 18:21:02 2017 open_tun
Wed May 31 18:21:02 2017 TAP-WIN32 device [Ethernet 2] opened: \\.\Global\{86A26EF3-9748-44FB-8C61-XXXXXXXX}.tap
Wed May 31 18:21:02 2017 Successful ARP Flush on interface [9] {86A26EF3-9748-44FB-8C61-XXXXXXXXX}
Wed May 31 18:21:02 2017 Block_DNS: WFP engine opened
Wed May 31 18:21:02 2017 Block_DNS: Using existing sublayer
Wed May 31 18:21:02 2017 Block_DNS: Added permit filters for exe_path
Wed May 31 18:21:02 2017 Block_DNS: Added block filters for all interfaces
Wed May 31 18:21:02 2017 Block_DNS: Added permit filters for TAP interface
Wed May 31 18:21:37 2017 env_block: add PATH=C:\WINDOWS\System32;C:\WINDOWS;C:\WINDOWS\System32\Wbem
Wed May 31 18:21:37 2017 env_block: add PATH=C:\WINDOWS\System32;C:\WINDOWS;C:\WINDOWS\System32\Wbem
Wed May 31 18:21:37 2017 env_block: add PATH=C:\WINDOWS\System32;C:\WINDOWS;C:\WINDOWS\System32\Wbem
Wed May 31 18:21:37 2017 env_block: add PATH=C:\WINDOWS\System32;C:\WINDOWS;C:\WINDOWS\System32\Wbem
Wed May 31 18:21:37 2017 env_block: add PATH=C:\WINDOWS\System32;C:\WINDOWS;C:\WINDOWS\System32\Wbem
Wed May 31 18:21:37 2017 SYSTEM ROUTING TABLE
(omitted)
Wed May 31 18:21:37 2017 SYSTEM ADAPTER LIST
(omitted)
Wed May 31 18:21:37 2017 Initialization Sequence Completed With Errors ( see http://openvpn.net/faq.html#dhcpclientserv )

Yes, I have seen this, but anyway I am a little bit disappointed. The only way is to use PPTP VPN server which is quite outdated. Sigh.