The Minecraft protocol uses a version number to distinguish between different protocol versions. Each new Minecraft version having a change in its protocol gets a new protocol version.
In lazymc you may configure what protocol version to use:
# -- snip --
[public]
# Server version & protocol hint.
# Sent to clients until actual server version is known.
# See: https://git.io/J1Fvx
version = "1.19.3"
protocol = 761
# -- snip --It is highly recommended to set these to match that of your server version to allow the best compatibility with clients.
- Set
public.protocolto the number matching that of your server version (see this list) - Set
public.versionto any string you like. Shows up in read in clients that have an incompatibel protocol version number
These are used as hint. lazymc will automatically use the protocol version of your Minecraft server once it has started at least once.