i have the ax5300 and cannot get gig speeds, i upgraded to the 1.2 gig speed and cannot get past 800meg down and i get 235 up. the upload has increased. i had two comcast techs out to my home and bot were able to pull 980meg, 1250meg from the comcast modem the XB-8 modem. i have changed all the cat5 cables and the problem lies with the deco, can i correct this isssue?  thanks.