AC88U OpenVPN TLS handshake Error

[XIYO]

I am not fluent in English so I used Google Translate.

Device, ac88u
Firmware, 384.19 (merlin)

unique,
All 8 ports are in use. (My device is port 1)
Wi-Fi also connects to 13 devices.

I changed the settings today and found that openvpn was not internally accessible and I tried several methods but still couldn't connect.
So I did a factory reset.
Tested on all iOS and Windows devices, but still can't connect.

Thanks in advance to those who answered.

Below is the log.

<Factory reset after OpenVPN run>

Nov 6 15:56:03 ovpn-server1[7579]: OpenVPN 2.4.9 arm-unknown-linux-gnu [SSL (OpenSSL)] [LZO] [LZ4] [EPOLL] [MH/PKTINFO] [AEAD] built on Aug 14 2020
Nov 6 15:56:03 ovpn-server1[7579]: library versions: OpenSSL 1.1.1g 21 Apr 2020, LZO 2.08
Nov 6 15:56:03 ovpn-server1[7580]: NOTE: the current --script-security setting may allow this configuration to call user-defined scripts
Nov 6 15:56:03 ovpn-server1[7580]: PLUGIN_INIT: POST /usr/lib/openvpn-plugin-auth-pam.so '[/usr/lib/openvpn-plugin-auth-pam.so] [openvpn]' intercepted=PLUGIN_AUTH_USER_PASS_VERIFY
Nov 6 15:56:03 ovpn-server1[7580]: Diffie-Hellman initialized with 2048 bit key
Nov 6 15:56:03 ovpn-server1[7580]: TUN/TAP device tun21 opened
Nov 6 15:56:03 ovpn-server1[7580]: TUN/TAP TX queue length set to 1000
Nov 6 15:56:03 ovpn-server1[7580]: /sbin/ifconfig tun21 10.8.0.1 netmask 255.255.255.0 mtu 1500 broadcast 10.8.0.255
Nov 6 15:56:03 ovpn-server1[7580]: ovpn-up 1 server tun21 1500 1621 10.8.0.1 255.255.255.0 init
Nov 6 15:56:03 ovpn-server1[7580]: Could not determine IPv4/IPv6 protocol. Using AF_INET6
Nov 6 15:56:03 ovpn-server1[7580]: Socket Buffers: R=[122880->122880] S=[122880->122880]
Nov 6 15:56:03 ovpn-server1[7580]: setsockopt(IPV6_V6ONLY=0)
Nov 6 15:56:03 ovpn-server1[7580]: UDPv6 link local (bound): [AF_INET6][undef]:1194
Nov 6 15:56:03 ovpn-server1[7580]: UDPv6 link remote: [AF_UNSPEC]
Nov 6 15:56:03 ovpn-server1[7580]: MULTI: multi_init called, r=256 v=256
Nov 6 15:56:03 ovpn-server1[7580]: IFCONFIG POOL: base=10.8.0.2 size=252, ipv6=0
Nov 6 15:56:03 ovpn-server1[7580]: Initialization Sequence Completed
Nov 6 15:56:17 rc_service: httpd 6750:notify_rc start_autodet
Nov 6 15:56:18 rc_service: httpd 6750:notify_rc start_webs_update
Nov 6 15:57:14 ovpn-server1[7580]: 192.168.1.12:60070 TLS: Initial packet from [AF_INET6]::ffff:192.168.1.12:60070, sid=b4be3126 a4370994
Nov 6 15:57:29 ovpn-server1[7580]: 192.168.1.12:64011 TLS: Initial packet from [AF_INET6]::ffff:192.168.1.12:64011, sid=ed09a537 0e5edd18
Nov 6 15:58:14 ovpn-server1[7580]: 192.168.1.12:60070 TLS Error: TLS key negotiation failed to occur within 60 seconds (check your network connectivity)
Nov 6 15:58:14 ovpn-server1[7580]: 192.168.1.12:60070 TLS Error: TLS handshake failed
Nov 6 15:58:14 ovpn-server1[7580]: 192.168.1.12:60070 SIGUSR1[soft,tls-error] received, client-instance restarting
Nov 6 15:58:29 ovpn-server1[7580]: 192.168.1.12:64011 TLS Error: TLS key negotiation failed to occur within 60 seconds (check your network connectivity)
Nov 6 15:58:29 ovpn-server1[7580]: 192.168.1.12:64011 TLS Error: TLS handshake failed
Nov 6 15:58:29 ovpn-server1[7580]: 192.168.1.12:64011 SIGUSR1[soft,tls-error] received, client-instance restarting

 

[eibgrad]

Looks to me like the OpenVPN server is defaulting to IPv6, when you probably want IPv4.

Nov  6 15:56:03 ovpn-server1[7580]: Could not determine IPv4/IPv6 protocol. Using AF_INET6

Try adding the following to the Custom Config field of the OpenVPN server.

proto udp4

 

[XIYO]

Thank you very much for answering!!
I have read threads related to IPv6. I also read the workaround. However, this option is not displayed in the GUI. Is it automatically defined as IPv6 in wrt?
Is the default setting of OpenVPN set to IPv6?

I did not intentionally set the file myself. I set it only with the GUI. Is this a bug? Or is it an intentional error in the firmware?