Nighthawk R8000 - 1000MB fiber but still slow wifi speeds and slow router speed after manual update

The iphone 12 might hit 800mbps but that'd be over wireless AX where it can connect at a 1200mbps link rate (and it'd have to be close to it).

If you looked at the tested specs of the R8000, its average throughput was around 250-300mbps over 5ghz. and over 2.4ghz it was hitting around 80-90mbps average. (2.4ghz is a much slower band)

Again, these are averages and under optimal conditions. You might get faster for period of time or slower depending on interference, device used, environment, etc. 

Something to keep in mind is that most devices, don't need super faster wireless speeds. Most 4k streaming is only hitting 25-40mbps. And gaming doesn't even need those speeds (more about latency with gaming). The super fast speeds are nice if you do a lot of large file downloading/backing up but it isn't going to make your movie play better. 

Smart connect works nice for some people, horrible for others. In congested environments it tends to struggle as it likes to have devices on the 2.4ghz. In my area, 2.4ghz is oversaturated with signals and devices that are on 2.4ghz, just work poorly. so try it with it on and off. the only downfall to off is that you have to choose which band to connect to. Make sure your streamers/gaming devices/high bandwidth devices are on the 5ghz. Put your low bandwidth devices on the 2.4ghz.