Excessive data usage

I just discovered I blew through about all of my cellular plan for this month… last Tuesday I used 3.5G. It’s the second month this happened, in November there was also one day I used about 3G.

Looking into data usage I found out Tailscale might be the cause of this issue… any idea what’s happening?

Hi @sevenymedia!
If you’re connecting to something that uses a lot of data, it’s possible.
Check to make sure you’re running Tailscale v1.2 throughout your network.
We’ll take a look to see what’s happening if you can share your logs with us.

I haven’t been using my phone differently than any other day (in which I spend a about 100-150M).

All devices/appliances on which I’m using Tailscale are using the latest version of the app.

I would share logs, but how do I do that from an iOS device?

I found your logs. (We have them here too, which is at least a tiny fraction of that 53 GB)

For now I’d recommend stopping Tailscale when not in use via iOS (in Settings > VPN and flipping the “Status: Connected” switch), not via the Tailscale app itself until we figure out what’s going on. (The iOS Settings way stops it much more aggressively.)

One thing I see is that one of your machines in particular (NUC) but really all of them to a lesser extent seem to be flipping back and forth between London and Frankfurt as their nearest “home” connection, even though I thought our code did a good job at preventing such oscillation. That then means they’re sending your phone a bunch of updates about where their new location is. At least in the next Tailscale release, that bandwidth is smaller. But they shouldn’t be flipping back and forth between London and Frankfurt anyway.

While that’s inefficient, it doesn’t explain 3.5 GB in a day. In the past 72 hours there have only been 300 flips back and forth.

I’ll look into it more with colleagues either tomorrow or next week.

Good to see that you’re able to trace the data usage. I think I confused days, the excessive usage occurred on Monday instead of Tuesday.

For now I switched off cellular usage for Tailscale on my phone.

Looking forward to a solution!

Any progress on this issue @bradfitz?

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We use tailscale for our iot network. For ethernet stations it is not a problem, but tailscale is using way to much traffic on mobile usage (3G, 4G).

This was confirmed by the tailscale support team.

I would say, you cant use it under this conditions - this is for us a really bad thing and we have to find an alternative to tailscale.

Yes, we are aware of this; it’s an area that we’re working on, and each release has gotten a bit better.

If it’s feasible, try to stop the Tailscale while not using it and start it when needed.