VM SH2 capping OpenVPN to about 3MB/sec

Rainmaker · 27 Apr 2014 at 03:32

For months now I've been turning slowly grey trying to resolve an issue. Our VM line is 152Mbps and (aside from some peak time congestion) we see that, pretty much. However when I connect to VPN (eg PIA) an Ubuntu torrent will cap out around 2.5MB to 3MB/sec.

Given that without the VPN an Ubuntu torrent will max the line, I figured at first the PC and/or torrent client setup was bust. I tried under Win 8.1, Debian, and Mac OS X and rotated various torrent clients (qBittorrent, Deluge, etc). Nothing worked - 18MB/sec without VPN and 3MB/sec with VPN. I tried at least half a dozen no-log VPN providers and they all provided the same issue regardless of encryption level, connection port etc.

I eventually accepted it was perhaps VM VPN shaping/throttling, but noted that the addition of a SOCKS5 proxy could speed things back up while simultaneously connected to the VPN. Weird. :confused:

Quite by accident tonight, after reinstalling Linux on my desktop and properly configuring the firewall and VPN port forward, I hit the 3MB/sec cap on my VPN while testing the Ubuntu 14.04 x64 download (my standard speed test for torrents).

In frustration, I threw the SH2 into modem only mode, and voila. The torrent hits full speed and no more issues.

So it seems that, once again, the SH2 is even more rubbish than I originally thought. Before leaving it in modem mode I tried disabling its firewall and so on but no changes, so I'll have to leave it in modem mode and pass the connection through to an IPFire box so I can keep wifi running on the LAN.

Does anyone have any thoughts as to what could be affecting VPN in the SH2, and how I might fix it without bridging it to a second box permanently?

Nexy · 27 Apr 2014 at 15:31

Have you tried switching your OpenVPN from UDP to TCP or vice versa, if your VPN provider supports it?

Rainmaker · 27 Apr 2014 at 17:32

Nexy said:
Have you tried switching your OpenVPN from UDP to TCP or vice versa, if your VPN provider supports it?

Yeah I've tried OpenVPN over TCP, UDP, SSL and SSH on every port possible with half a dozen different suppliers (trials ftw). It's definitely some kind of bug/limitation with the SH2.

I'm considering shelling out for an Asus '56U but for now I'm leaving the SH2 in modem only mode, and passing through the connection to a custom built IPFire box (Linux firewall/router with a wifi hotspot).

asim18 · 27 Apr 2014 at 19:47

I had same issues with OpenVPN. I thought it was because the software NIC adapter was showing something silly like 10Mbps.

Rainmaker · 28 Apr 2014 at 13:40

asim18 said:
I had same issues with OpenVPN. I thought it was because the software NIC adapter was showing something silly like 10Mbps.

Yeah I've heard that before on the PIA forums, but apparently that's just a peculiarity of TUN adapters under Windows, and doesn't actually limit the speed. Since I've taken the SH2 out of the equation IPFire has been serving the network flawlessly with way better speeds.

As I said, I was going to buy an Asus but I've just realised that for a couple of quid more I can build a new AM1 platform microATX box with an SSD. It'd have full network routing and hardware firewall capabilities and still be able to act as a server and local NAS. Awesome.