I've just installed a new Tp-Link AX3000 (Archer AX50) router.  Checking the speed with the OOKLA app on an iPad Gen 4, about 2-3 feet from the router, the download speed of the 5Ghz band is 339Mbps and on the 2.4Ghz band is only 9Mbps.  On both bands the upload speed is 12Mbps.  FING shows 21 devices on the 5Ghz and 20 on the 2.4Ghz.  
This seems like a crazy difference!  Is this reasonable or, perhaps the router has a problem or I have some wrong setting?  I'd sure appreciate it is someone could shed some light on this. 
 

Thanks for any advice you might be able to offer.