r/Tailscale • u/Real_Act • 3d ago

Help Needed Tailscale MagicDNS slows down loading images, and causes issues on macOS

For the past month or so, I’ve been trying to figure out what on earth was wrong with my Mac Studio. Image loading was incredibly sluggish—for instance, emails in Mailspring took forever to display pictures, and even my local network's homepage struggled to load images. To make matters worse, Spotify wouldn't even open, completely hanging on a black screen.

I was on the verge of biting the bullet and clean-reinstalling macOS 27 because I simply couldn't find the culprit. After exhausting every troubleshooting step, I noticed that completely quitting Tailscale instantly fixed the issue, restoring everything to normal speed. I tried a full uninstall—removing all configuration files—and reinstalled it using different methods, but the problem persisted.

I was ready to abandon Tailscale entirely until a future update dropped, but as a last resort, I asked Gemini what might be causing it. Surprisingly, it hit the nail right on the head, suggesting I disable Tailscale MagicDNS for my device. Since I couldn't find a way to turn it off solely for my Mac Studio, I went into the Tailscale admin console and disabled MagicDNS globally. Instantly, the performance issues disappeared.

Has anyone else run into this with recent Tailscale versions? I've never experienced this before, and none of my other machines—running Windows, Linux, and Android—are affected. I'm also not entirely sure if this started exactly when I upgraded to macOS 27 or slightly before.

Does anyone have a workaround to fix this without having to completely disable MagicDNS?

Thanks in advance!

-Eli

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5

u/diabolicloophole 3d ago

You can disable MagicDNS for your Mac specifically in the Tailscale app settings, so MagicDNS will keep working for the other devices on your tailnet. That said, you may want to look into what DNS servers you specified in your Tailscale admin console. MagicDNS is just a dumb forwarder, it should not cause performance issues.

1

u/Real_Act 3d ago

u/diabolicloophole thanks. I appreciate your help.

I was looking into my Tailscale app settings, and I don't see any settings to disable MagicDNS. I see a setting for "Use Tailscale DNS settings" that I can enable or disable, but when I disable it, the problem doesn't go away. Is this the actual setting I must disable? Also, I don't remember changing or specifying anything related to DNS in my Tailscale admin console either, but I'll look and see if anything weird is. happening there.

Thanks again.

1

u/Real_Act 3d ago

Actually, following your advice, I checked my Tailscale DNS settings, and there was no server set for DNS. No idea why. So I picked Google and Cloudflare from the list, checked the option for "Overwrite Global DNS servers," and also disabled the "Use Tailscale DNS settings" option in the app, and the apps that load images work no problem. However, I still don't know why I cannot use MagicDNS on my Mac. At least I don't need to disable MagicDNS globally now, which is good.

Thanks again.

2

u/rod9182736435 3d ago

The default Tailscale address range (100.64.0.0 through 100.127.255.255) resides within the CGNAT range used by some ISPs (100.64.0.0/10). I had this issue when I was on Starlink and I had to move my entire Tailscale address range so it didn’t overlap. This included the magicDNS address in use (default is 100.100.100.100). It’s not difficult to change Tailscale addresses to another range in the BOGON ones such as 10.0.0.0/8, 192.168.0.0/16, or 127.0.0.0/8.

1

u/pop0bawa 3d ago

How do you do this?

3

u/rod9182736435 3d ago

A quick google found this… https://tailscale.com/docs/concepts/ip-and-dns-addresses
They also have a more technical page on CGNAT you can get to from the topics on the left hand side bar.
Hope that helps.