Autoban the IP of a kicked player for some time
After a player got kicked from a server, he usually can just reconnect right away. Autobanning for at least a short time (10 minutes up to maybe one or two hours) would prevent an immediate reconnect without creating a too big impact on accidental miss-kicks. Autoban could ban a /24 IPv4 net (I don't know what would be a good range for IPv6 - does xonotic support IPv6 anyways?)