Unfortunately you are approx 700ft from box, pair bonding requires approx 3K give or take a few hundred ft.
As far as your coax I would do a test with your dvr and use a cat from the 3801 and I think you will see a great deal of improvemet. I personally would use cat5 for all boxes, but the dvr at a minimum. Also I would assume the tech is feeding the rg from the NID with coax as well, it's the default for most techs unfortunately. If poss run your own cat 5 from nid directly to rg, move it if its easier, I suggest right next to the dvr and backfeed the rest of the coax from there. This way you can just plug in a cat5 patch cable from the rg to dvr.