Isolated Node and Timeout Configuration

How can I isolate my nodes from all types of incoming connections and interaction with the Bitcoin network?

I need to perform heavy queries on my nodes and it requires all the hardware resources. thank you.

And my timeout doesn’t work…

rpcuser=user
rpcpassword=test
rpcbind=127.0.0.1
rpcallowip=127.0.0.1
rpcport=8332
daemon=1
maxconnections=20
maxuploadtarget=250
txindex=1
maxuploadtarget=20
rpcclienttimeout=1800

# Disable incoming connections
listen=0