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OpenVPN incredibly slow compared to PPTP

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davewolfs

Regular Contributor
I have an issue with OpenVPN on slow connections. It is significantly slower than the routers built in PPTP. To the point that it is simply not usable for certain things eg VNC/RDP.

I don't know if this is the nature of the protocol or how I have set things up.

I do see the following warnings from my client logs:

NOTE: Options consistency check may be skewed by version differences
WARNING: 'version' is used inconsistently, local='version V4', remote='version V0 UNDEF'
WARNING: 'dev-type' is present in local config but missing in remote config, local='dev-type tun'
WARNING: 'link-mtu' is present in local config but missing in remote config, local='link-mtu 1560'
WARNING: 'tun-mtu' is present in local config but missing in remote config, local='tun-mtu 1500'
WARNING: 'proto' is present in local config but missing in remote config, local='proto TCPv4_SERVER'
WARNING: 'comp-lzo' is present in local config but missing in remote config, local='comp-lzo'

Is it possible that compression is not being used?
 
Well here is a solution.

The tutorial here:

http://www.howtogeek.com/60774/connect-to-your-home-network-from-anywhere-with-openvpn-and-tomato/

Shows the usage of TCP as the desired protocol. Changing to UDP seems to have completely resolved the issue.

So I tried switching to UDP as a test, and when connecting from my Android phone from outside my local LAN (turned off WIFI and just used 4G) it seemed to work OK. But then I tried some test clients on my LAN and it would not connect. The log showed packets being rejected with a message suggesting I needed to remove a "remote" option. I researched that and found advice to change the "client" in my config file to "float". I did that but that failed as well. Any ideas?
--
bc
 
So I tried switching to UDP as a test, and when connecting from my Android phone from outside my local LAN (turned off WIFI and just used 4G) it seemed to work OK. But then I tried some test clients on my LAN and it would not connect. The log showed packets being rejected with a message suggesting I needed to remove a "remote" option. I researched that and found advice to change the "client" in my config file to "float". I did that but that failed as well. Any ideas?
--
bc

I discovered that to make it work from inside my LAN I had to replace the server IP with its local IP (e.g. it is normally set to nnnnnnnn.asuscomm.com, to get a client to connect from inside the LAN when the protocol is UDP, I have to set it to 192.168.1.1). It'd be nice if there were some way to configure the client so that it would just work whether I am inside or outside the LAN (e.g. some config parameter in the server to tell it that 192.168.1.1 is equivalent to whatever nnnnnnnn.asuscomm.com resolves to).
--
bc
 
I discovered that to make it work from inside my LAN I had to replace the server IP with its local IP (e.g. it is normally set to nnnnnnnn.asuscomm.com, to get a client to connect from inside the LAN when the protocol is UDP, I have to set it to 192.168.1.1). It'd be nice if there were some way to configure the client so that it would just work whether I am inside or outside the LAN (e.g. some config parameter in the server to tell it that 192.168.1.1 is equivalent to whatever nnnnnnnn.asuscomm.com resolves to).
--
bc

Try creating a custom hosts file with an entry containing your IP and your hostname. See the Wiki for info on how to use custom config files. It should hopefully override any DNS entry.
 
Performance-wise, OpenVPN will always be slower than PPTP because it uses much stronger encryption. There are ways you can limit the performance impact tho (for my own use, the RDesktop performance is pretty close to what it used to be when I was using PPTP).

- Limit your keys to 1024 bits (anything higher is overkill and will degrade performance)
- Stick with one of the AES encryption codecs as these are optimized in the OpenSSL implementation of Asuswrt-Merlin
 

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