apk add fails with Permission denied

[robstoll]

As simple use case I tried the following

docker run --rm docker:git apk add --update zip
Unable to find image 'docker:git' locally
git: Pulling from library/docker
aad63a933944: Already exists 
69846a6807b3: Pull complete 
5517540127c6: Pull complete 
da4bc653673c: Pull complete 
7d6a82484b25: Pull complete 
98d7178a08bc: Pull complete 
06fedb666dd1: Pull complete 
145837c41213: Pull complete 
Digest: sha256:c061e3894336ba0dbf26144b7d816f59cedb2d0304fb11cc8bab21f9fabcf4be
Status: Downloaded newer image for docker:git
fetch http://dl-cdn.alpinelinux.org/alpine/v3.11/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.11/community/x86_64/APKINDEX.tar.gz
ERROR: http://dl-cdn.alpinelinux.org/alpine/v3.11/main: Permission denied
WARNING: Ignoring APKINDEX.70f61090.tar.gz: No such file or directory
ERROR: http://dl-cdn.alpinelinux.org/alpine/v3.11/community: Permission denied
WARNING: Ignoring APKINDEX.ca2fea5b.tar.gz: No such file or directory
ERROR: unsatisfiable constraints:
  zip (missing):
    required by: world[zip]

Then I tried:

wget  http://dl-cdn.alpinelinux.org/alpine/v3.11/main/x86_64/APKINDEX.tar.gz
--2020-04-09 13:21:11--  http://dl-cdn.alpinelinux.org/alpine/v3.11/main/x86_64/APKINDEX.tar.gz
Resolving dl-cdn.alpinelinux.org (dl-cdn.alpinelinux.org)... 195.186.208.193
Connecting to dl-cdn.alpinelinux.org (dl-cdn.alpinelinux.org)|195.186.208.193|:80... connected.
HTTP request sent, awaiting response... 403 Forbidden
2020-04-09 13:21:11 ERROR 403: Forbidden.

Any idea why?

[cab105]

Attempting to hit the website directly, I see:
Your client address is unknown.

[robstoll]

works again for me. I guess someone has fixed something

[cab105]

Did manage to confirm that it appears the CDN hosting alpinelinux.org is blocking my primary ISP. Switching to an alternate ISP did work-around my issue.