this has just been posted by developer of PCARS dash
Hi All,
I have an email from one of the pCars Dash users today who had been having lag issues with his iPhone6, his problem turned out to be his router. This is what he said
"Been messing about with the router and its settings tonight. I know the Xbox one normally runs on 2.4ghz (automatically) but I have deleted all devices from 5ghz, renamed it so it runs as a different wirless connection and connected the Xbox, and iPhone and IPad all on the new network. There are only these three devices running.
Bothe devices now work seamlessly on UDP 3.
I know it's fixed for now (hopefully for good) but though i would tell you the work around I have done if anybody else has the same problem!"
So it sounds like he might have had some devices connecting by 5Ghz, while some were connected on 2.4Ghz. I would imagine the packet routing between the wifi two networks probbaly resulted in the lag. Moving them to a single network fixed his issue. The same may occur if you have multiple networks (SSIDs) setup even on the same frequency, or if you have range extenders or multiple APs doing seamless roaming.
hope it helps