1.12.1 just came out, and you kinda have to update it. It would just be easier for all of us, making us able to join the server without changing versions.
Frankly I don't care about the Minecraft version. This server could be on Terraria for all I care. All the same, I'd like some new blocks. There's a new server coming out with an updated version, but I think I can be safe in saying it's unlikely this server will update given the new one coming out. If the server could be made compatible without actually changing its version, that would be fabulous.