Icon
Upload a 64×64 pixel PNG named server-icon.png into the server root. Restart. Anything else (wrong size, JPG, transparent edges) is silently ignored; open the PNG in any image editor and resize it to exactly 64×64.
MOTD
The two lines under your server name in the list come from motd in server.properties.
- Colours:
§followed by a code (agreen,baqua,cred,eyellow,lbold,rreset). Example:§bPengu SMP §7- §aSeason 3. - Line break:
\n. - Longer text and hover graphics: plugins like MiniMOTD or ServerListPlus let you write it in plain colour tags and rotate messages.
What else players see
- Player count and names on hover (Paper:
hide-online-playersinserver.propertieshides names). - Ping bars: depends on their distance to Frankfurt, nothing to tune.
- Version compatibility: a red "Incompatible" means their client version differs. ViaVersion (a plugin) lets newer clients join an older server.