If I want to login in DSM from a Hotel or another remote location, I can use Quickconnect or Tailscale. What is the advantage of using Tailscale?
The two options are not really comparable, Tailscale is a mesh VPN, Quickconnect is just a way to expose your device to the Internet. If you are the only one who needs to connect to your NAS, I would recommend Tailscale, so you do not expose anything to the Internet. The disadvantage is that you need to install Tailscale on all devices that need to connect to each other: all these devices will be on the same network, and nothing else will see them or be able to connect to them.
Personally, I do not use Quickconnect; I have a couple of services that I want exposed to the Internet, but I prefer to run them in Docker containers, and use Tailscale Funnels, which allows me to expose something publicly.
Other options would be OpenVPN or WireGuard (Tailscale is based on the latter). If Iām not mistaken, Will has a tutorial on how to set up OpenVPN.
Sorry for my late reply. Thank you very much for your answer. It is very clear!