I have a somewhat large VPN network which works perfectly with "mtu-test". On one client, the mtu-test fails because of a broken MTU discovery so I have create a special configuration on the server for this client (because "fragment 1300 on the client only breaks everything).

networking - OpenVPN - Socket bind failed on local address I am trying to start the openVPN server so that I can login remotely using username: demo and password: demo, but openVPN server is failing to start. =865193 fragment = 0 Thu Aug 29 12:02:46 2013 us=865221 mtu_discover_type = -1 Thu Aug 29 12:02:46 2013 us=865244 mtu_test = 0 Thu Aug 29 12:02:46 2013 us=865266 mlock = DISABLED Thu Aug 29 12 OpenVPN tweaking - Ars Technica OpenForum Oct 03, 2007 I/OpenVPN Starting openvpn D/OpenVPN fragment = 0 D D/OpenVPN OpenVPN 2.4-icsopenvpn [git:icsopenvpn_627-cff5e3e9c3ac08df] android-14-x86 [SSL (OpenSSL)] [LZO] [SNAPPY] [LZ4] [EPOLL] [MH] [IPv6] built on Jun 6 2015 D/OpenVPN library versions: OpenSSL 1.0.1j 15 Oct 2014, LZO 2.07

2. Update your package list and install the necessary OpenVPN packages using the commands below. Note: These are two separate commands. Updating your package list will take a moment. Run the second command afterwards. opkg update opkg install openvpn-openssl luci-app-openvpn. 3.

The OpenVPN documentation says that using "fragment" adds 4 bytes to the OpenVPN header. We did indeed see that now we could ping to a maximum of 1287 bytes (compared to 1291 previously). Up to 1287 is fine, 1288 to 1308 bytes would not ping, 1309 and above worked. Presumably a 1309 byte raw packet translates into a 1400 byte OpenVPN encrypted OpenVPNに接続したときに、接続が不安定になる問題を解消する …

OpenVPN MTU settings - personal-vpn

OpenVPN - SME Server Jun 27, 2017