Hi guys i get the same problem as the people above wit hthe high bufferbloat through xr500, i've managed to find a work around by using my sky hub > r1 > xr500 and i manage to get 1ms jitter like that, but i'd much rather take the r1 out the setup (i'm using CC on r1) instead of cc on xr500 since it doesn't seem to work properly, my ping plotter drops packets when it's activate with the upload side of the speedtest having jitter of 200ms+.
Not massively sure what the problem is since it isn't my line (tested without any router 20ms jitter) I think QOS is putting stress on the xr500 somehow. Everything else works fine apart from qos.