Describe the problem in details.
What's the firmware version? Is it up to date?

Vivian wrote

Describe the problem in details.
What's the firmware version? Is it up to date?

The signal I get is about -75 to -78dBm on 5GHz and -63dBm on 2.4GHz


There are 0 devices in the vicinity working on 5GHz (but many on 2.4GHz).
My devices (Phone & Tablet) are just in the adjoining room in a small apartment.


If I shift just a few steps (about 5 feet) the 5GHz signal strength changes to around -67dBm.


Devices used on 5GHz
Samsung Galaxy A5-SM-A500G
Samsung Galaxy Note 8.0 - GT-N5100


Devices used on 2.4GHz
HP ProBook 4530s

Device Information
AC750 Wireless Dual Band Gigabit ADSL2+ Modem Router
Model No. Archer D2


Firmware Version :0.6.0 0.11 v003e.0 Build 150427 Rel.60143n
Hardware Version :Archer D2 v1 00000000

Try different channels like 157, 153, 149 etc. Try channel width 40MHz or 20MHz.

Vivian wrote

Try different channels like 157, 153, 149 etc. Try channel width 40MHz or 20MHz.

Already did that too.