Cannot update Debian container in Docker

Running Docker for Windows 18.09.2 with Docker Desktop *31259, trying to update an Debian container via apt-get update.

First I pull the latest images:
    > docker pull debian
Using default tag: latest
latest: Pulling from library/debian
5ae19949497e: Pull complete
Digest: sha256:903779f30a7ee46937bfb21406f125d5fdace4178074e1cc71c49039ebf7f48f
Status: Downloaded newer image for debian:latest
> docker run -d -ti --name d1 debian
> docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
d1fce4047033        debian              "bash"              2 seconds ago       Up 1 second                             d1

Then I connect to the container and try to make an update:

$ winpty docker exec -ti d1 bash
[email protected]:/# uname -a
Linux d1fce4047033 4.9.125-linuxkit #1 SMP Fri Sep 7 08:20:28 UTC 2018 x86_64 GNU/Linux
[email protected]:/# apt-get clean
[email protected]:/# apt-get update
Err:1 buster/updates InRelease
  503  Service Unavailable [IP: 80]
Err:2 buster InRelease
  503  Service Unavailable [IP: 80]
Err:3 buster-updates InRelease
  503  Service Unavailable [IP: 80]
Reading package lists... Done
W: Failed to fetch  503  Service Unavailable [IP: 80]
W: Failed to fetch  503  Service Unavailable [IP: 80]
W: Failed to fetch  503  Service Unavailable [IP: 80]
W: Some index files failed to download. They have been ignored, or old ones used instead.
[email protected]:/# ping
PING ( 56(84) bytes of data.
64 bytes from icmp_seq=1 ttl=37 time=18.5 ms
--- ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 6ms
rtt min/avg/max/mdev = 18.406/19.176/20.597/1.012 ms
    [email protected]:/# wget
bash: wget: command not found
[email protected]:/# curl
bash: curl: command not found

As you can see, the update fails but I have internet connection. Tried several times, but have no luck.
Because it’s the same behavior as when I try to pull Ubuntu or something else, I assume not a simple reason behind.
I have tested the download of one of these files on a busybox via wget and it works. Also when I try to download the site via browser. So what’s happens here?

Source: StackOverflow