Have you ever seen those two piece keychains that just snap together? I have half of on on my net and two of the other half. One of the other halves is on the back of my fishing vest and the other on is on my pontoon. I just snap it on and I have never lost a net like I have sometimes found nets with a magnet attached. My net has a stretchy cord attached to it and I can reach most things. But the keychain pops apart with the press of a button if I can't quite reach with it attatched.
I picked these up a year ago. The hook can be closed with a pair of pliers, once you decide where/to what you want to hook them to (I use a loop on the side of my pack). Other magnet connected with an eyelet I drilled/glued into the end of my net handle.
Have an elastic cord attached, just in case, but have not had any issue with the net pulling loose. Magnets are just strong enough to keep the net in place busting through bankside willows and such, but not so strong that you can't pull it free when you need it.
Magnet on top middle back of vest, with a stretch cord hooked on lower left side of vest. When I hook a fish I just tug on the net, it drops and is hanging by my left hand when I get the fish in. Very handy.