Bridging XBee signal with LAN-cable

Hey there

Currently have 3 RPi’s in play. They all have an attached XBee, RTC and Accelerometer.

The idea is to be able to send commands and recieve packages over larger distances using the XBee modules with XCTU. With our current setup this is possible however say the wireless XBee signal would encounter a thick metal door then the entire system would fail (wireless signal not strong enough to pass the door).

So what could be a solution to this problem is having two RPi’s near this door (RPi1 on one side and RPi2 on the other side of the door) and then connect them with a LAN-cable.

The thought is that the recieved XBee signal that RPi1 gets (from a PC) can be transferred through the LAN-cable to RPi2 so RPi2 also recieves this XBee signal. Following that the XBee signal should then be carried on from RPi2 to RPi3 through the already working wireless setup (since the signal managed to pass the thick metal door).

Any ideas on how this could be done?