| OpenVPN on Clearwire ISP doesn't workI have an openvpn server running on tcp port 443 (the server is on the "cloud"). I used to connect to it while I was on Verizon DSL with no problems. I switched to Clearwire and now, even though I can connect no data comes through from the server (eg the browser will keep saying "sending request" with nothing happening).
I tried pinging the server using its local vpn address (10.30.0.1) and found that:
I can ping fine as long as the size of the packet is less than about 1700 bytes.
So, this works as long as it's running:
ping -s 1700 10.30.0.1
But once I do this, I no longer get any response anymore:
ping -s 2000 10.30.0.1
Now, once I send that ping, even the following doesn't get me a response
ping -s 1 10.30.0.1
In terms of browsing: if I try browsing google right after vpn connects, the result is "waiting for response" and the page doesn't open. If I close that tab and try again, I get "sending request" and nothing happens.
Any idea as to what might be going on here? |
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| Clearwire is 3G/4G wireless service, correct?
Any VPN is going to have trouble with high-latency links, such as wireless. Your connection is going to vary greatly depending on signal strength, and how many other calls/data is going through the tower your device is connected with.
VPN would prefer that all data arrive sequentially, and at consistent latency - with wireless all bets are off, sometimes data never arrives, or arrives too late.
You've proved with a larger ping size that your connection has trouble, what you don't know is if Clearwire has specifically configured something to dis-allow that, or to break up larger packets, or if your connection is just terrible - any of which is why you don't get a response. |
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| said by supergeeky:You've proved with a larger ping size that your connection has trouble, what you don't know is if Clearwire has specifically configured something to dis-allow that, or to break up larger packets, or if your connection is just terrible - any of which is why you don't get a response.
Any idea as to how I can troubleshoot this? Without VPNing, my connection is very stable and Clearwire's (wimax is 4G I guess?) modem-router always shows 5/5 signal reception. |
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 whfsdudePremium
join:2003-04-05
Washington, DC | reply to vajorie
Clearwire uses a MTU of 1400.
In the OpenVPN client config put.
mssfix 1400 |
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| Thanks for the help.
Just an update for others who might be having this problem...
mssfix didn't help, so I tried mtu-test, which told me that it wouldn't make sense to run that test when the tunnel is over tcp. So I changed it to udp (on the server and client) and run the test. The test reported no anomalies in terms of mtu, and lo and behold, the connection works fine over udp without --fragment or --mssfix. |
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