@Im your Friend Ty for the links especially the heads up on cable modems. It certainly feels like I'm jumping through hoops trying to mitigate the pain of a bad modem. Cutting my download bandwidth in
half nets some nice results on the bufferbloat test, but applying adaptive QoS on top of that seems to keep my ping incredibly stable. Will probably give the ER-X a spin at another location, but I really want to get the most out of this ac68u right now. Half bandwidth is not very exciting so hopefully Merlin and this script will yield some improvement. Then there is the issue of sky high ping on 2.4ghz while downloading, which I am not very optimistic about
Many, many modems and routers were needlessly replaced when the problem was
cabling and connectors.
You can have all 5 steps done perfectly but your connection can still be garbage because of a loose connector, damaged cable, corrosion at the pole, et al. (Notice how the most probable cause of these issues is missing from that list--it's a popular oversight.)
Check layer 1 first. Educate yourself on RG-6, dielectric grease, cable installation practices (find satellite installation training; they do it correctly, where, ironically, cable companies do not), drip loops, and grounding and termination. Assume the guy installing the stuff didn't follow standard installation practices (I've not met one who has and I've moved around a lot, needing installation more than most).
After checking layer 1 (cables and connectors), look at your modem's diagnostics and statistics to check your signal levels and error counts. If you have an SB6183, look at its spectrum analyzer (browse to port 8080 on your cable modem). Visit your ISP's forum and look at what the tech-savvy people say.
After you've established your WAN connection is good, if you still have issues, check layer 1 on your LAN: cables get damaged; there are many fake Cat5 cables out there (copper coated, not copper wire), bad crimps, etc. After checking that, see if you have problems with all clients or some/one in particular and diagnose.