Download speeds cut in half

Not sure what happened but for the last week my speeds have dropped in half out of the blue, thought it was some issues with my isp but it wasn't. I installed my old router and im peaking at 330mpbs, i put my ac56u back with 380.57 and its back down to 150mpbs, i disable qos and it goes up to 220mbps.
I just switched to 380.58 and its the same issue.