How to run a TCP/IP game on a cluster - bash

Question

I wrote a TCP/IP game that involves one server and two clients who then play the game, write some statistics about it and close. (It's two AIs playing a game)
I wrote a shell script that opens those three child scripts. However, currently no statistics are being written. Since sometimes the setup stage (clients connect to server) works and sometimes not even that, I assume that those children are wrongly distributed over the cores and can't communicate with the server. (?)
How would I generally solve this problem? Perhaps not with tmux? Running SGE, version 6.2u3beta.
Here's my shell script:
#!/bin/bash
# This script is supposed to take a json problem instance (name is problemNNNNN.json)
# Then open server with -i problem$SGE_TASK_ID.json -o -p open-port,
# then open two clients with -p open-port.
#$ -S /bin/bash
#$ -m n
#$ -l h_vmem=4G
## Tasks
#$ -t 1-1
#$ -cwd
problem_file=problem$SGE_TASK_ID.json
function find_open_port(){
# Ports between 49152 - 65535 are usually unused.
port=$(shuf -i '49152-65535' -n '1')
# Then check if port is open
if lsof -Pi :$port -sTCP:LISTEN -t >/dev/null ; then
find_open_port
else
# There is no service currently running on this port
return $port
fi
}
find_open_port
tmux new-session -d -s '$SGE_TASK_ID' "python server.py -p $port -i $problem_file"
sleep 1
tmux split-window -v -t '$SGE_TASK_ID' "python client.py -p $port"
sleep 1
tmux split-window -h -t '$SGE_TASK_ID' "python client.py -p $port"
exit