Steam can only connect in TCP mode, cannot join any gameservers

Question

A few months ago Steam stopped being able to log in. I thought there may be a server outage so I waited a few days but when it still didn't work I started investigating. I ran through Valve's Network Troubleshooting steps and found that the last one (launching steam in TCP mode via a command line parameter) fixed my issue. Unfortunately while I can now launch Steam I can't connect to any servers once I'm in-game.

I would like to get UDP connectivity working again. It seems that a number of other Steam users encountered the same problem at around the same time as I did. Some of them report that deleting ClientRegistry.blob fixes the issue, but this does not work for me. Users with the same router as me (Asus RT-AC68U) report that disabling NAT Acceleration fixed the issue for them, but again this didn't work for me. I believe I installed WireShark at about the same time as the issues started, but I have since uninstalled it (and WinPcap too) and the issue persists.

I'm wondering what diagnostic tools are available for an issue like this, or if anyone has suggestions of what I should try next.

I'm not sure if it's related, but every now and then almost every program on my computer will go Not Responding. One time I happened to have Task Manager open and I clicked Analyze Wait Chain on explorer.exe (Not Responding) and it said something about waiting on the network. So I believe my computer may have some serious networking issues.

Thanks,

YM

EDIT: Done some more testing, here's what I've found.

Steam works perfectly on a Linux machine on the same network

Steam on my computer will not work without -tcp even when I am at someone else's house. (Coincidentally, they also have an RT-AC68U, but Steam works fine on their computer)

This suggests the issue is with my computer, not with my router.

Steam will not work without -tcp in safe mode (with networking). It does work when used with -tcp in safe mode.

Steam isn't the only program with issues. I cannot see or connect to any servers in any game, not just Steam games. Additionally, I cannot download any torrents.

I have disabled IPv6 on my computer without any improvement.

I would prefer not to format/reset my computer.

Solution 1

You should first determine if your UDP connectivity issue is specific to Steam or Windows itself. You need to test underlying UDP connectivity and confirm that is working before trying to fix Steam.

Netalyzr is a useful tool for spotting a variety of connectivity problems including doing a variety of UDP tests:

http://netalyzr.icsi.berkeley.edu/

[Edit]

Your tests show basic UDP connectivity is good, however the following entry in your results stick out:

NAT support for Universal Plug and Play (UPnP) (?): Not tested – An I/O error occurred during the test. The test result code is 34.

Putting aside NAT traversal/UPNP, the I/O error indicates some software on your computer is blocking certain UDP traffic to your router, e.g. Windows firewall or another firewall. If turning off all firewall applications completely does not resolve it, it could be other drivers or applications hooked into the IP stack, e.g. the Wireshark you previously mentioned. I would disable firewall globally from control panel => windows firewall, not wf.msc.

I'd also recommend uninstalling and reinstalling your network card driver(s) as well as doing a full IP stack reset using the following commands:

netsh int ip reset

netsh winsock reset

netsh int ipv4 reset

(See guide here: http://www.hanselman.com/blog/TheNuclearOptionResettingTheCrapOutOfYourNetworkAdaptersInVista.aspx)

Solution 2

Since you mentioned that torrents don't work either, I would assume that your computer is having a problem with all UDP traffic. In this case, I would suggest you uninstall every network driver and let Windows reinstall the drivers when you reboot. Basically try to clean completely your network configuration. At worse you'll lose saved networks but that's not so bad compared to losing half of internet.

The other thing I would also try is to connect to a VPN that uses TCP and check if the UDP traffic is forwarded correctly or not. That might help finding where the problem is.

Comments

[ganesh]

Can you install the steam client on another computer and test that from without your network? That way you know if the problem is local to your computer or somewhere in your network setup (either the local network or your ISP which may try to do 'smart' things).

[Joshua Walsh]

I can install it on a Linux box but I don't have another Windows box lying around. Will try it tonight.

[Joshua Walsh]

Did some research, added extra details to OP.

[Jet]

If you can't even download torrent, but everything's fine in another computer on the same network then it may be a software related problem. Can you run a LiveCD/DVD/USB (e.g. Ubuntu's Try before Install)? Put it on your USB stick, boot from it and try to download a torrent. Does it work?

[Joshua Walsh]

I thought my firewall was disabled, but when I went into wf.msc it turned out I still had a domain firewall active. I turned that off and I still have the same issue.

[Joshua Walsh]

Torrenting works when booting Ubuntu off a USB, but the USB doesn't have enough space to test Steam.

[Joshua Walsh]

I am currently running no anti-virus software.

[Joshua Walsh]

I already uninstalled/reinstalled Steam. (Accidentally deleted half my games and hours worth of modding in the process, thank god for backups) It unfortunately has not fixed my issue.

[td512]

This doesn't uninstall steam, rather, it only forces steam to redownload itself, making sure you have no left over bits.

[td512]

The only other thing you could do is... reset your PC

[Joshua Walsh]

I'd really rather not reset my PC, but I may have to. I really doubt it's an issue with Steam considering I'm experiencing issues with many programs.

[td512]

@YM_Industries if you are going to reset your PC, use ninite to quick reload apps, it's good at that.

[Joshua Walsh]

Wow that is an awesome tool. My results are here, I can't see any glaring issues.

[qasdfdsaq]

I've edited my answer in response to your results - please see above.

[Joshua Walsh]

You legend! The firewall was already disabled and uninstalling/reinstalling my drivers did nothing, but I used all the commands at the link you provided (not just the ones you mentioned in your post) and it worked! Thanks!