Hi alzhao,
I installed firmware v2.255. Openvpn does start now
but there are still a lot of error messages in the log. In particular add route and delete route give problems. The very first time (just after flashing) I started openvpn there were no messages. Then, stopping and starting generated error messages concerning the route add and route delete. I will adjust a part of the system log.
Mon Jun 5 09:39:11 2017 daemon.notice openvpn[3606]: OpenVPN 2.4.0 mips-openwrt-linux-gnu [SSL (OpenSSL)] [LZO] [LZ4] [EPOLL] [MH/PKTINFO] [AEAD]
Mon Jun 5 09:39:11 2017 daemon.notice openvpn[3606]: library versions: OpenSSL 1.0.2g 1 Mar 2016, LZO 2.08
Mon Jun 5 09:39:12 2017 daemon.notice openvpn[3609]: TCP/UDP: Preserving recently used remote address: [AF_INET]x.x.x.x:443
Mon Jun 5 09:39:12 2017 daemon.notice openvpn[3609]: UDP link local: (not bound)
Mon Jun 5 09:39:12 2017 daemon.notice openvpn[3609]: UDP link remote: [AF_INET]x.x.x.x:443
Mon Jun 5 09:39:12 2017 daemon.notice openvpn[3609]: NOTE: UID/GID downgrade will be delayed because of --client, --pull, or --up-delay
Mon Jun 5 09:39:15 2017 daemon.notice openvpn[3609]: [server] Peer Connection Initiated with [AF_INET]x.x.x.x:443
Mon Jun 5 09:39:16 2017 daemon.notice netifd: Interface ‘VPN_client’ is enabled
Mon Jun 5 09:39:16 2017 daemon.notice netifd: Network device ‘tun0’ link is up
Mon Jun 5 09:39:16 2017 daemon.notice netifd: Interface ‘VPN_client’ has link connectivity
Mon Jun 5 09:39:16 2017 daemon.notice netifd: Interface ‘VPN_client’ is setting up now
Mon Jun 5 09:39:16 2017 daemon.notice openvpn[3609]: TUN/TAP device tun0 opened
Mon Jun 5 09:39:16 2017 daemon.notice openvpn[3609]: do_ifconfig, tt->did_ifconfig_ipv6_setup=0
Mon Jun 5 09:39:16 2017 daemon.notice openvpn[3609]: /usr/sbin/ip link set dev tun0 up mtu 1500
Mon Jun 5 09:39:16 2017 daemon.notice netifd: Interface ‘VPN_client’ is now up
Mon Jun 5 09:39:16 2017 daemon.notice openvpn[3609]: /usr/sbin/ip addr add dev tun0 local 10.8.0.22 peer 10.8.0.21
Mon Jun 5 09:39:16 2017 daemon.notice openvpn[3609]: GID set to nogroup
Mon Jun 5 09:39:16 2017 daemon.notice openvpn[3609]: UID set to nobody
Mon Jun 5 09:39:16 2017 daemon.notice openvpn[3609]: Initialization Sequence Completed
Mon Jun 5 09:39:17 2017 user.notice firewall: Reloading firewall due to ifup of VPN_client (tun0)
Mon Jun 5 09:39:39 2017 daemon.err openvpn[3609]: event_wait : Interrupted system call (code=4)
Mon Jun 5 09:39:39 2017 daemon.warn openvpn[3609]: ERROR: Linux route delete command failed: external program exited with error status: 1
Mon Jun 5 09:39:39 2017 daemon.warn openvpn[3609]: ERROR: Linux route delete command failed: external program exited with error status: 1
Mon Jun 5 09:39:39 2017 daemon.warn openvpn[3609]: ERROR: Linux route delete command failed: external program exited with error status: 1
Mon Jun 5 09:39:39 2017 daemon.warn openvpn[3609]: ERROR: Linux route delete command failed: external program exited with error status: 1
Mon Jun 5 09:39:39 2017 daemon.warn openvpn[3609]: ERROR: Linux route delete command failed: external program exited with error status: 1
Mon Jun 5 09:39:39 2017 daemon.notice openvpn[3609]: /usr/sbin/ip addr del dev tun0 local 10.8.0.22 peer 10.8.0.21
Mon Jun 5 09:39:39 2017 daemon.warn openvpn[3609]: Linux ip addr del failed: external program exited with error status: 2
Mon Jun 5 09:39:39 2017 daemon.notice netifd: Network device ‘tun0’ link is down
Mon Jun 5 09:39:39 2017 daemon.notice netifd: Interface ‘VPN_client’ has link connectivity loss
Mon Jun 5 09:39:39 2017 daemon.notice netifd: Interface ‘VPN_client’ is now down
Mon Jun 5 09:39:39 2017 daemon.notice openvpn[3609]: SIGTERM[hard,] received, process exiting
Mon Jun 5 09:39:39 2017 daemon.notice netifd: Interface ‘VPN_client’ is disabled
Mon Jun 5 09:39:50 2017 daemon.notice openvpn[4426]: OpenVPN 2.4.0 mips-openwrt-linux-gnu [SSL (OpenSSL)] [LZO] [LZ4] [EPOLL] [MH/PKTINFO] [AEAD]
Mon Jun 5 09:39:50 2017 daemon.notice openvpn[4426]: library versions: OpenSSL 1.0.2g 1 Mar 2016, LZO 2.08
Mon Jun 5 09:39:50 2017 daemon.notice openvpn[4427]: TCP/UDP: Preserving recently used remote address: [AF_INET]x.x.x.x:443
Mon Jun 5 09:39:50 2017 daemon.notice openvpn[4427]: UDP link local: (not bound)
Mon Jun 5 09:39:50 2017 daemon.notice openvpn[4427]: UDP link remote: [AF_INET]x.x.x.x:443
Mon Jun 5 09:39:50 2017 daemon.notice openvpn[4427]: NOTE: UID/GID downgrade will be delayed because of --client, --pull, or --up-delay
Mon Jun 5 09:39:53 2017 daemon.notice openvpn[4427]: [server] Peer Connection Initiated with [AF_INET]x.x.x.x:443
Mon Jun 5 09:39:54 2017 daemon.notice openvpn[4427]: TUN/TAP device tun0 opened
Mon Jun 5 09:39:54 2017 daemon.notice openvpn[4427]: do_ifconfig, tt->did_ifconfig_ipv6_setup=0
Mon Jun 5 09:39:54 2017 daemon.notice openvpn[4427]: /usr/sbin/ip link set dev tun0 up mtu 1500
Mon Jun 5 09:39:54 2017 daemon.notice openvpn[4427]: /usr/sbin/ip addr add dev tun0 local 10.8.0.22 peer 10.8.0.21
Mon Jun 5 09:39:54 2017 daemon.notice netifd: Interface ‘VPN_client’ is enabled
Mon Jun 5 09:39:54 2017 daemon.notice netifd: Network device ‘tun0’ link is up
Mon Jun 5 09:39:54 2017 daemon.notice netifd: Interface ‘VPN_client’ has link connectivity
Mon Jun 5 09:39:54 2017 daemon.notice netifd: Interface ‘VPN_client’ is setting up now
Mon Jun 5 09:39:54 2017 daemon.notice netifd: Interface ‘VPN_client’ is now up
Mon Jun 5 09:39:54 2017 daemon.warn openvpn[4427]: ERROR: Linux route add command failed: external program exited with error status: 1
Mon Jun 5 09:39:54 2017 daemon.notice openvpn[4427]: GID set to nogroup
Mon Jun 5 09:39:54 2017 daemon.notice openvpn[4427]: UID set to nobody
Mon Jun 5 09:39:54 2017 daemon.notice openvpn[4427]: Initialization Sequence Completed
Mon Jun 5 09:39:55 2017 user.notice firewall: Reloading firewall due to ifup of VPN_client (tun0)
Mon Jun 5 09:41:09 2017 daemon.err openvpn[4427]: event_wait : Interrupted system call (code=4)
Mon Jun 5 09:41:09 2017 daemon.warn openvpn[4427]: ERROR: Linux route delete command failed: external program exited with error status: 1
Mon Jun 5 09:41:09 2017 daemon.warn openvpn[4427]: ERROR: Linux route delete command failed: external program exited with error status: 1
Mon Jun 5 09:41:09 2017 daemon.warn openvpn[4427]: ERROR: Linux route delete command failed: external program exited with error status: 1
Mon Jun 5 09:41:09 2017 daemon.warn openvpn[4427]: ERROR: Linux route delete command failed: external program exited with error status: 1
Mon Jun 5 09:41:09 2017 daemon.warn openvpn[4427]: ERROR: Linux route delete command failed: external program exited with error status: 1
Mon Jun 5 09:41:09 2017 daemon.notice openvpn[4427]: /usr/sbin/ip addr del dev tun0 local 10.8.0.22 peer 10.8.0.21
Mon Jun 5 09:41:09 2017 daemon.warn openvpn[4427]: Linux ip addr del failed: external program exited with error status: 2
Mon Jun 5 09:41:09 2017 daemon.notice netifd: Network device ‘tun0’ link is down
Mon Jun 5 09:41:09 2017 daemon.notice netifd: Interface ‘VPN_client’ has link connectivity loss
Mon Jun 5 09:41:09 2017 daemon.notice netifd: Interface ‘VPN_client’ is now down
Mon Jun 5 09:41:09 2017 daemon.notice openvpn[4427]: SIGTERM[hard,] received, process exiting
Mon Jun 5 09:41:09 2017 daemon.notice netifd: Interface ‘VPN_client’ is disabled