How do I replace my router's built in wireless antenna with a high gain antenna?
Built in antennas are generally connected to an IPEX Female connector located on the circuit board.
Buy an IPEX to SMA FEMALE BULKHEAD RP pigtail.
Open your router and connect the IPEX end of the pigtail to the circuit board where the built in antenna is connected. Drill a hole on the back of the router case and mount the SMA FEMALE BULKHEAD RP end of the pigtail. Add an external antenna with an SMA MALE connector.