OpenVPN stops working once 60+ clients are connected

chamsoft

I have been using OpenVPN 2.2.2 for a while and we have just encountered a problem which appears to be related to the number of clients connecting. When we reach about 60 connections new clients still connect, but they can't access any resources on the server. The only way I can resolve this is to stop the VPN server, delete the ipp.txt and openvpn-status.log from the config folder and restart the VPN. But this is only a temporary fix of course.

I noticed in the ipp.txt file that client IP addresses are allocated in multiples of 4 (e.g. 10.7.0.4, 10.7.0.8, 10.7.0.12, etc). It seems to me a quick solution to this is to get it to allocate all available addresses. Is there a configuration setting somewhere to change this behavior?

By the way, I have read somewhere about the limitation in Windows that prevents more than 60 clients when using TCP but we have always used UDP so I don't think that is the problem.

VPNTutorials

I believe you are using topology net30. You need to change that to topology subnet in your config file.

More info on the man page: https://community.openvpn.net/openvpn/wiki/Openvpn23ManPage

chamsoft

Thank you so much VPNTutorials. I simply added the directive "--topology subnet" to my server config file, restarted the service and it appears to work fine using sequential IP addresses. I have tested it on Windows XP and Windows 8 so far.

VPNTutorials

chamsoft wroteThank you so much VPNTutorials. I simply added the directive "--topology subnet" to my server config file, restarted the service and it appears to work fine using sequential IP addresses. I have tested it on Windows XP and Windows 8 so far.

Glad that worked for you 🙂

----------
VPN Tutorials / VPN Forums