Setting up Development Environment Fails

Following the instructions, I’ve cloned HA/core. Running the setup downloads a bunch of stuff (docker, python, …) and then fails with errors:

...
#5 89.83 Get:21 http://deb.debian.org/debian bullseye/main amd64 libuv1 amd64 1.40.0-2 [132 kB]
#5 93.24 Get:22 http://deb.debian.org/debian bullseye/main amd64 cmake amd64 3.18.4-2+deb11u1 [5593 kB]
#5 115.0 Get:23 http://security.debian.org/debian-security bullseye-security/main amd64 libavutil-dev amd64 7:4.3.4-0+deb11u1 [437 kB]
#5 117.3 Get:24 http://security.debian.org/debian-security bullseye-security/main amd64 libswresample-dev amd64 7:4.3.4-0+deb11u1 [121 kB]
#5 118.3 Get:25 http://security.debian.org/debian-security bullseye-security/main amd64 libavcodec-dev amd64 7:4.3.4-0+deb11u1 [5514 kB]
#5 120.0 Err:25 http://security.debian.org/debian-security bullseye-security/main amd64 libavcodec-dev amd64 7:4.3.4-0+deb11u1
#5 120.0   Error reading from server. Remote end closed connection [IP: 151.101.42.132 80]
#5 149.4 Err:22 http://deb.debian.org/debian bullseye/main amd64 cmake amd64 3.18.4-2+deb11u1
#5 149.4   Connection timed out [IP: 151.101.42.132 80]
#5 181.3 Err:26 http://security.debian.org/debian-security bullseye-security/main amd64 libavformat58 amd64 7:4.3.4-0+deb11u1
#5 181.3   Could not connect to debian.map.fastlydns.net:80 (151.101.42.132), connection timed out Could not connect to security.debian.org:80 (151.101.130.132), connection timed out Could not connect to security.debian.org:80 (151.101.2.132), connection timed out Could not connect to security.debian.org:80 (151.101.66.132), connection timed out Could not connect to security.debian.org:80 (151.101.194.132), connection timed out [IP: 151.101.42.132 80]
#5 181.3 Err:27 http://security.debian.org/debian-security bullseye-security/main amd64 libpostproc55 amd64 7:4.3.4-0+deb11u1
#5 181.3   Unable to connect to security.debian.org:http: [IP: 151.101.42.132 80]
#5 181.3 Err:28 http://security.debian.org/debian-security bullseye-security/main amd64 libswscale5 amd64 7:4.3.4-0+deb11u1
#5 181.3   Unable to connect to security.debian.org:http: [IP: 151.101.42.132 80]
...

How can I get around this?

Thanks!
Bernhard