Using any private server violates Supercell’s Terms of Service. While playing on a private server will not get your main account banned (as they use completely separate servers), discussing it or sharing your main account details on private platforms can put your official account at risk.
While generic private servers (which run the current version of the game with infinite resources) are incredibly common, finding a working server dedicated strictly to an older version (like V6, V7, or V8) is much more difficult. Here is the current state of working legacy servers: 1. The Retro Server Projects clash of clans private server old version work
Finding old versions of Clash of Clans that still work can be a challenge. Here are some steps players can take: Using any private server violates Supercell’s Terms of