The power levels on some of your downstream channels are out of spec (-6 to +10 is in spec).
Could you post your upstream data please?
Do you have a device like below attached between your HUB and cable to the wall socket?
One other thing to consider, since you are getting around 90Mbps (Including overheads), is the ethernet connection could be running at 100Mbps, rather than gigabit, which would limit the speed to your device.
Ok, if you can power off the HUB, remove the attenuator, and screw the cable from the wall directly into the HUB, the downstream power levels will rise by roughly 6dB, bringing them close to 0, or slightly positive, which is what you want.
This will not, however, fix your upstream power levels.
Power the HUB back on and post a fresh set of stats.