apt update failing with connection failed

Today, attempting apt update was failing:

Hit:1 http://deb.debian.org/debian bullseye InRelease
Err:2 http://security.debian.org/debian-security bullseye-security InRelease
  Connection failed [IP: 151.101.166.132 80]
Err:3 http://deb.debian.org/debian bullseye-updates InRelease
  Connection failed [IP: 151.101.166.132 80]
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
All packages are up to date.
W: Failed to fetch http://deb.debian.org/debian/dists/bullseye-updates/InRelease  Connection failed [IP: 151.101.166.132 80]
W: Failed to fetch http://security.debian.org/debian-security/dists/bullseye-security/InRelease  Connection failed [IP: 151.101.166.132 80]
W: Some index files failed to download. They have been ignored, or old ones used instead.

I was able to access the resources in my browser, which was redirected to https.

So I updated /etc/apt/sources.list, changing http to https throughout and then apt update completed without errors.

Hit:1 https://deb.debian.org/debian bullseye InRelease
Get:2 https://deb.debian.org/debian bullseye-updates InRelease [44.1 kB]
Get:3 https://security.debian.org/debian-security bullseye-security InRelease [48.4 kB]
Get:4 https://security.debian.org/debian-security bullseye-security/main Sources [192 kB]
Get:5 https://security.debian.org/debian-security bullseye-security/main amd64 Packages [236 kB]
Get:6 https://security.debian.org/debian-security bullseye-security/main Translation-en [154 kB]
Fetched 675 kB in 5s (138 kB/s)                            
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
68 packages can be upgraded. Run 'apt list --upgradable' to see them.

The original sources had been working for well over a year. It seems http is no longer supported.