Server for system update of Debian in Sweden ?
In future, please ask these sort of questions on the user support channels:
My installed Debian version 9.5, is set up to use a Debian mirror in Denmark, which it also uses automatically when I install packages.
When I make a system update, it will automatically connects to a Swedish server with the address 188.8.131.52 SKYCA-3 Sweden. Is that OK?
This IP address is a Fastly CDN node. So I assume you are not using a
specific Debian mirror in Denmark but are instead using
deb.debian.org, which is backed by the Fastly CDN. If your system is
likely to move to different places, using the CDN is the best option
since it should be available close to anywhere you might travel. If
your system is a server or is unlikely to change location, you might
like to use the Debian mirror provided by your ISP or one of the
closer mirrors such as ftp.dk.debian.org. Please note that in case of
downtime, ftp.dk.d.o could be repointed to other mirrors.