Problems with Virgin Media: Warcraft is too slow

Are you having problems with unplayably low connection speeds? Is your internet service provider Virgin Media? Warcraft players in the UK and elsewhere in Europe using Virgin Media as an ISP have reported ongoing problems with their connection to the game. If you think you may be affected, we’ve got the details (along with a possible fix) here.

What’s the problem with Virgin Media?

The problem seems to stem from the new Launcher and background downloader which shipped as part of Cataclysm. This gets a bit technical, so bear with us. The background downloader uses peer-to-peer technology to allow you to download World of Warcraft updates from other Warcraft players as well as from the main servers. This has always been the case, but at Cataclysm’s release (specifically, the upgrade from patch 3.3.5 to patch 4.0.1) the ‘ports’ used by the game were expanded. Instead of using TCP port TCP 3724 (a special “address” on your computer, allowing data to be transmitted and received), this patch used ports 3724, 1119, 1120, 4000 and 6112-6114. That meant that a lot more data could be transmitted and received at one time, which meant that you could download the patch much faster. Unfortunately, it also meant that WoW used a lot more network traffic that it otherwise would.

Because of this Virgin Media, in combination with their network partners Telia, downgraded the World of Warcraft application. It’s now classified on their network in the “peer-to-peer” category, rather than the “gaming” category it once inhabited. That, in turn, means that WoW receives less network traffic and, crucially, a lower network traffic priority across Virgin Media’s network.


Is it fixed yet?


WoW no longer transmits data over such a wide range of ports (we’re back to using good old ports 3724 and 6881, fact fans). Virgin Media reported this issue as fixed at the end of July 2011. Blizzard also view the problem as now being resolved. However, many posters to the Virgin Media support forums and to the Blizzard forums are claiming that the problem persists.

Blizzard themselves are adamant that the problem lies outside their control, and it would certainly appear that the issue is one that only affects Virgin Media customers.

What can I do about it?

The good news (if you’re a Windows user) is that there may be a short-term fix which you can implement yourself. If it works, it’ll bring your speed back to playable levels, which should keep you going until Blizzard and Virgin Media can work out a more permanent solution.

The fix is an easy, one-line modification to your network settings. The full details can be found in this thread by Dronthank on the Blizzard EU forums. As with any modification of your computer’s settings, you do this at your own risk. It’s not an official fix sanctioned by either Blizzard or Virgin Media. Representatives from both companies have, however, made posts pointing affected users towards that thread as a potential fix.

Read Dronthak’s post to get the full details, but the basic fix is as follows:

This DOES appear to be effective. Please redirect people to this thread.

Please, post results. Let us know how this works!

To do this on a Windows PC(Windows 7, Windows Vista):

Run CMD; Start>All Programs>Accessories>Command Prompt, right click to run as administrator

Type the command;

netsh interface ipv4 set subinterface “Local Area Connection” mtu=900 store=persistent


netsh interface ipv4 set subinterface “Wireless Network Connection” mtu=900 store=persistent

To reset this, re-type the line that worked for you and replace the “900” with “1500”

FOR WINDOWS XP USERS; Download TCP optimiser. I’ve seen this recommended in the thread, although I’m unsure if it actually works as I’m not having this problem.

(thanks to Torchwood for that)

To do this on a Mac:

Apply icon > System Preferences > Network > Ethernet / Airport

Advanced > Ethernet tab > Select “Configure: Manually” (from Automatic) >

Change MTU from “Standard (1500)” to “Custom” and enter 900

It’s still not fixed!

If you’re still having problems, you should make a post on the Blizzard forums. You’ll make the Blizzard Customer Service guys’ jobs an awful lot easier if you follow a few simple rules:

  • Check the forums to see if there’s already a thread about your problems.
  • Don’t assume that your problem is a resurgence of an existing issue – resurrecting a dead thread is no use to anybody. If in doubt, create a new thread.
  • However frustrated you may be feeling, remember that Blizzard’s Customer Support team are as keen to solve the problem as you are to have it solved, so be polite. Don’t be that guy.
  • Make your post useful. Provide the information that will be needed to solve your problem. At a minimum, you should provide details of the problems you’re having, details of what speed you’re getting and what speed you think you should be getting, and probably a traceroute and pathping as well.

Quote taken directly from Dronthak’s thread on the EU forums.

Have you had problems playing World of Warcraft on a Virgin Media connection? Did Dronthank’s fix work for you? Let us know you experiences in the comments.