I want to understand, as all rocket uses LAN cable and switches to communicate between stages. why can't they implement wifi module which will even reduce weight and power?

I want to understand, as most rocket uses LAN cable and switches to communicate between stages. Is it possible to replace with WiFi? Although it's will be complex system but one idea to make each stages wireless. How can I improve reliability? With combination of wireless and wireless can we communicate within its structure. How to improve coupling between antennas?