I fish with a backpack, and I attach the net to the backpack. I’ve tried attaching the net with carabiners (too fiddly) and magnets (not strong enough; I’d often find myself bushwhacking alongside a stream only to find my net caught by a branch several feet behind me). For the past six months or so, I’ve been using a side lock buckle. This is your standard webbing buckle, the kind that you squeeze on the side to open up. This is the exact buckle (3/4″ size) that I use. I have the net dangling off the bottom of the left shoulder strap. To both attach the buckle to the backpack and attach the net to the other half of the buckle, I’ve used a couple different sizes of zip ties.
This works really well. I can easily clip and unclip the buckle to grab the net, and the buckle never accidentally comes undone.