I have 50 servers built on CentOS 7 which will become end of life in 2024. So I will build my server on Ubuntu Server. I find that Ubuntu 20.04 extended support is to 2030. On the other hand, Ubuntu 21.10 extended support is to 2022, which means the new version has less support! I know the latest version usually has more support than the early one.
Please advise which version of Ubuntu Server I should install on my servers.
Ubuntu 21.10 is not a LTS or long-term-support release thus has no extended support. LTS releases are the first release of an even year, 2021 is not even, and 21.10 is the last non-LTS in the cycle that began with 20.10, 21.04, 21.10 that completes with the next LTS in Ubuntu 22.04 LTS.
Ubuntu 21.10 (or the 2021-October release) are intended to be upgraded to the next LTS release which is Ubuntu 22.04 LTS which will be released in 2022-April (see https://discourse.ubuntu.com/t/jammy-jellyfish-release-schedule/23906 for the release schedule).
Ubuntu LTS releases have been 6.06, 8.04, 10.04, 12.04, 14.04, 16.04, 18.04, & 20.04. ie. the first release of the even year; the 2006 release wasn't April but June thus 6.06; the only exception to the April release intention of subsequent releases of Ubuntu. The format of releases being year.month of release.
Ubuntu LTS (Long Term Support) releases are released every even year in April. This means 20.04 is LTS, with the next LTS release being 22.04.
The recommended upgrade path for production servers is from one LTS release to the next. So in almost any cirucumstance, LTS releases (which is 20.04 for now, and later 22.04) are recommended for production servers.
See more here: What is an Ubuntu LTS release?
