TLDR: When using IPv6 exclusively, I wasn't able to connect to certain popular servers and services. For example, github.com After so many years.

Why we can't have nice and modern things

I was creating a new server. And this time I wanted to be modern and bleeding edge so I chose to not use an IPv4 address and have only an IPv6.

And I also wanted to use Tailscale to access this resource only from the devices in the same network.

So far so good. The setup was easy and smooth.

Fired up docker, installed the services I needed etc. Great.

Now, did I manage to connect the resources between them? Yes, I did. In this particular case, I had to exchange larger files. For backup purposes.

And that's when the problems started.

The upload speed from one device to the server was... abismal... around 120kb/s.

My initial isssue was that there were too many new variables introduced and had no idea who took the blame.

The docker containers were new and there were some services I haven't used before. Transferring files through Tailscale was new. And a bunch of other small things.

So here I was:

=> Slow upload speeds through Tailscale to the server. What do?

Well, tailscale status to the rescue. It told me that the connection was not direct. It was relayed. I knew I had the firewalls setup correctly so that wasn't the issue. Why wasn't it direct? Can I force it?

Again, too many unknowns. Luckily, a friend of mine said that IPv4 might be the culprit. So I tested it out. Bought and attached the address to the server. Rebooted. Retried. Instead of 120kb/s, I got 30 mb/s. Now that's more like it!

And yes, tailscale status now showed a direct connection.

ps. Oh and that GitHub issue? It was easily fixable through a proxy. But still...