I have the Motorola 6141 modem and the Asus ac68r and I get lag when I play games on my ps4 or xbox one especially when someone else uses the internet. I plugged directly into the modem and that did improve things. My download is 20mbs and my upload is 2. I even get some lag on my computer even when there are only 2 computers going. I actually returned both the router and the modem in place for 2 new ones because I thought there may be a problem with one of them and still the same problem.. Wont let me port forward, the qos does not make a difference and the dmz does nothing. I have new lines in my house I had time warned come out again to check the lines and they everything is fine on their end I guess. I am starting to wonder if the modem and the router are not compatible.