I am driving crazy with this issue. I have a temporal SOHO server sitting behind a NAT (cannot touch this), and I need it to have a public facing IP.
So a set up an OpenVPN server on a VPS (With 2 public IP), and configured OpenVPN to bridge L2 and lend one of the public IP's to the SOHO server.
All is working ok, but I am having a very strange issue, upload speed from SOHO server to VPS through VPN is around 5 Mbps, whereas download speed is perfectly normal at ~90 Mbps (100M network).
At first I thought it would be some buffer problem, even CPU bottleneck, but after trying the following points, I am desperate.
I am using UDP mode. TCP mode only degraded a little bit the download speed, but consistently got the same poor upload speed. Even the basic test described here triggered the same problem.
Things I tried:
- Changing buffers, 0 on both sides, 393216 on both, 0 on server and 393216 on client.
- fast-io
- Compression On and Off
- Switching encryption off
- Even building OpenVPN from sources on the SOHO!
Always getting consistent < 10 Mbps speed on upload from SOHO server to VPS. CPU usage on upload is only at 7%, whereas on download it reaches 40%.
Normal speeds outside VPN between this servers is at network maximum.
The SOHO server is a HP Microserver G8, which features a Intel(R) Celeron(R) CPU G1610T @ 2.30GHz. It does not include AES-NI.
I don't know what more to try, I started to think that OpenVPN maybe it's not the culprit, but I don't know where else to look.
Thanks for your time, and keep on with this great community.
