[This is common reference for people who have download problems.]
You reported a download problem. Download problems has little to do with esp-open-sdk, and many of them are local and intermittent. Options you have:
Retry in some time.
Contact your ISP to ensure a problem is not on your side of the Internet.
Contact the site with whose downloads you have problems.
Find another mirror of the needed file, and download it manually.
If you are sure that particular site is down for extended time, check the latest version of crosstool-NG, and if it's affected, report this issue to crosstool-NG upstream. (Note that esp-open-sdk uses an older snapshot of crosstool-NG, backports are usually not done, so you'd need to do p.4 locally anyway.)
[This is common reference for people who have download problems.]
You reported a download problem. Download problems has little to do with esp-open-sdk, and many of them are local and intermittent. Options you have: