Unstable link.

Grigoriy Bilichenko

We use openvpn about 2 years, but 2 weeks ago some problems occuired. Some UDP-based clients sometimes can't connect to server. And sometimes can. But almost always speed of this connection is insufficient. It so slowly that client not always can request his settings over dhcp. I tried remake client and server configs on tcp-based connection. Tcp clients always connects and anways received dhcp settings, but speed of this is very slow, insufficient even for windows rdp. Ping between client and server has big timings. My provider is guilty for this? If yes, what requirements for openvpn it violates? PS Sorry for my english.
Server and client config for tcp and udp settions differents only "proto" string.

server config

port 9998
proto udp
dev tap
dev-node tap-bridge
mode server
tls-server
ca ca.crt
cert server.crt
key server.key
dh dh1024.pem
keepalive 10 120
comp-lzo
persist-key
persist-tun
status bridge-status.log
verb 6
crl-verify crl.pem

client config

client
dev tap
proto udp
remote 82.151.114.226 9998
resolv-retry infinite
nobind
persist-key
persist-tun
ca ca.crt
cert client.crt
key client.key
ns-cert-type server
comp-lzo
verb 6

7zipped logs both tcp and udp client and server.

Grigoriy Bilichenko

Ping from network behind openvpn server to tcp connected client

PING 192.168.0.143 (192.168.0.143) 56(84) bytes of data.
64 bytes from 192.168.0.143: icmp_req=1 ttl=128 time=44.0 ms
64 bytes from 192.168.0.143: icmp_req=2 ttl=128 time=132 ms
64 bytes from 192.168.0.143: icmp_req=3 ttl=128 time=123 ms
64 bytes from 192.168.0.143: icmp_req=4 ttl=128 time=250 ms
64 bytes from 192.168.0.143: icmp_req=5 ttl=128 time=200 ms
64 bytes from 192.168.0.143: icmp_req=6 ttl=128 time=36.8 ms
64 bytes from 192.168.0.143: icmp_req=7 ttl=128 time=224 ms
64 bytes from 192.168.0.143: icmp_req=8 ttl=128 time=151 ms
64 bytes from 192.168.0.143: icmp_req=9 ttl=128 time=87.2 ms
64 bytes from 192.168.0.143: icmp_req=10 ttl=128 time=168 ms

--- 192.168.0.143 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9007ms
rtt min/avg/max/mdev = 36.825/142.011/250.849/68.548 ms

Flood ping client

PING 192.168.0.143 (192.168.0.143) 56(84) bytes of data.
..    
--- 192.168.0.143 ping statistics ---
10 packets transmitted, 8 received, 20% packet loss, time 121ms
rtt min/avg/max/mdev = 25.507/48.953/69.007/15.479 ms, pipe 6, ipg/ewma 13.520/43.127 ms

If number of packets is more than 10, packet loss more too.

Ping 8.8.8.8 from server for show quality of internet connection

PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_req=1 ttl=252 time=30.7 ms
64 bytes from 8.8.8.8: icmp_req=2 ttl=252 time=31.1 ms
64 bytes from 8.8.8.8: icmp_req=3 ttl=252 time=31.1 ms
64 bytes from 8.8.8.8: icmp_req=4 ttl=252 time=30.8 ms
64 bytes from 8.8.8.8: icmp_req=5 ttl=252 time=31.1 ms
64 bytes from 8.8.8.8: icmp_req=6 ttl=252 time=30.7 ms
64 bytes from 8.8.8.8: icmp_req=7 ttl=252 time=31.4 ms
64 bytes from 8.8.8.8: icmp_req=8 ttl=252 time=31.5 ms
64 bytes from 8.8.8.8: icmp_req=9 ttl=252 time=69.5 ms
64 bytes from 8.8.8.8: icmp_req=10 ttl=252 time=72.2 ms

--- 8.8.8.8 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9013ms
rtt min/avg/max/mdev = 30.763/39.057/72.264/15.935 ms

Flood ping 8.8.8.8

PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
   
--- 8.8.8.8 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 145ms
rtt min/avg/max/mdev = 30.766/31.212/32.289/0.450 ms, pipe 3, ipg/ewma 16.189/31.227 ms

Grigoriy Bilichenko

Rewrited config for udp server and clients, were added next options

fragment 1300
mssfix

After that, connection always work. But speed for windows rdp still unsufficient, windows drawing is very slow; interface works unresponsive.