I am a happy owner of the DG834PN router from Netgear.
It is a little old but I am satisfied from its speed and wifi coverage.

However, I always felt I had to hack this router. The router by default does not support an external antenna. This is fine, since it covers every corner of my appartment. But I had to add an external anntenna connector anyway…

So here it is:

I bought male-female rp-sma cable and cut it in the middle.

I soldered the female part on the internal antenna circuit and used some tape to keep the cable from moving.

Here is the first soldering point:

…and the other one:
*Your can use your multimeter to search for soldering points.

Drilled a hole on the backpanel and glued the connector.

Closed the router case carefully and connected it to power!
Everything works fine! (I need to clean that desk.)

I do not have a way to measure if the signal was improved inside the house, since it was maximum anyway. But I will try around the house and keep you updated!