When player with lower version join the server its all black and idk what to do

When someone join the server with lower version like 1.8.9 everything is black and he cant move as you can see on the picture i sent

HELP ME MY SERVER DONT START

I wait from like 20min

it dont start

hello

i u se viabackwards plugin and viarewind plugin with paperMC softoare

I still have the same issue

when someone join with lets say 1.8.9 its all black i tried to join with 1.12.2 i can join but everything i black and i cant move

can you come check and help me to solve the problem the ip is Gomexus.aternos.me

Hello

can you help me there is guy who come and crash my server can you help me and give me plugin for this to stop him from doing it