Consistent crashes - Suspecting port forwarding issue

Hi all! I started Zwifting about a week or two ago and ever since it’s been one crash/freeze after another. I’ve been doing some digging and what I see consistently in the logs is this:

[12:19:04] NETCLIENT:[INFO] UDP metrics {StC Rx: 950, Rx error: 0, CtS Tx: 104, Tx error: 0}

[12:19:04] NETCLIENT:[WARN] UDP connection timeout (1 so far), reconnection attempt 1

The UDP connection time-out makes me suspect it’s a port forwarding issue. I have already set that up according to Zwift’s advice (TCP 80 & 443 for incoming and outgoing, UDP 3022 for incoming), but the issue persists. So my guess is I have to do some more digging to uncover why the port forwarding isn’t playing nice.

It’s very random, I’ve been able to complete 1 freeride and 2 ZA workouts without freezes, but every segment ride, group ride, or race and several freerides and workouts have resulted in crashes. Last Sunday I had 4 crashes in the space of an hour. Zwift freezes on me and that’s that. Some environment sound keeps playing, but the only way to get back into it is force closing and restarting.

Some background info:

  • Running on a four month old Windows 10 laptop that fits the specs, graphics card is just a built-in Intel (drivers are up-to-date), the framerate or resolution isn’t high, but it’s stable and good enough.
  • I’ve already made sure Bluetooth is off (as to not to interfere with ANT+), Onedrive sync is also off and Garmin Express isn’t running
  • I’ve tried plugging in a cable, doesn’t make a difference. Same goes for trying out both the 2,4Ghz and 5Ghz frequency
  • Doesn’t matter in what world or what type of activity

Hoping someone can confirm that by the above error log the issue is indeed the port forwarding. That would bring me one step closer to finally getting to Zwift in peace :wink:

I really don’t think the crashes are cause by you forwarding ports (my guess is you are actually opening ports in your firewall) to your Zwift PC since you can start Zwift unplug your network cable and continue riding.

The issue could be your graphics card, ANT+ dongle or overheating.

Thanks Paul. I’m quite sure it’s not overheating, because the laptop doesn’t get hot. When I lay on the couch all Sunday afternoon watching cycling streaming to my TV from the laptop, it gets a bit warm, but that doesn’t happen when Zwifting.

I’ve chucked some log files in the Zwiftalizer, that says my ANT+ could be better, but is ok. I’ll see if I can get a hold of a USB cable to move the ANT+ away from the laptop.

Regarding the graphics card, any advice on how to determine whether that is the issue? Not much of a techie unfortunately (I was already quite proud of myself I diagnosed it this far).

You can look at the FPS in Zwiftalizer what was your P5 and average FPS.

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If you’ve manually modified the prefs.xml file to enhance the graphics, may want to back that out. I had an issue with Zwift crashing on the France routes and was able to resolve it by restoring the original prefs.xml file.

Thanks for the help Gerrie! Average FPS is about 35, P95 around 45 if I look at the averages across my rides.

So I can’t seem to embed an image, but Zwiftalizer is saying ANT isn’t amazing, so I’ll try to improve that. One consistent thing I see in the Zwiftalizer analysis is a network reconnection right at the point of the crash. With the UDP error message, I still feel this could be the issue.

@Daniel_Goehring, haven’t modified anything, don’t think that is it (wouldn’t know how to do it, haha)

If there was a network error you would not see other riders/runners within Zwift.

You can disconnect your network connect after you start riding/running and you will remain in-game but you will be all a lone. Near the end of your ride you can reconnect and save/sync your ride/run. I have done this many times.