I downloaded both Geth and lighthouse on my Linux server and I managed to connect both of them together in the mainnet and geth start syncing and downloading blocks ... ect These are the used command lines:
Geth
sudo ./geth --authrpc.addr localhost --authrpc.port 8551 --authrpc.vhosts localhost --authrpc.jwtsecret /tmp/jwtsecret console
lighthouse
sudo ./lighthouse --network mainnet beacon_node --http --execution-endpoint http://localhost:8551 --execution-jwt /tmp/jwtsecret
But I wasn't able to do that in the testnet What am I supposed to change in the command line to make both connect to each other and sync and start working in the testnet