HERE 2 HDOP VIA CAN >=1 ,CAN'T achieve desired GS speed

MY QUAD running Arducopter 4.0.4.rc3 with HERE 2 GPS via CAN .

i have planned mission for mapping at WP_speed = 12 m/s ,it was not maintained this speed as it always it goes up-to 11 m/s but not Desired speed(12 m/s).
i also noticed that HDOP on the mission planner is always near to 1 its not go below this value even my GPS got almost 23 satellite with clear sky (placed drone on center of cricket ground).
2020-08-04 13-02-29.log.param (18.4 KB)

please some review my log and give me feedback.

Your log did not contain an actual flight. Could you please send a log where you tried to reach the 12m/s ?

Oh sorry I will send actual log . thank you.

@Eosbandi sorry for the wrong log this is the actual log please kindly look at .