Low Signal form RB Metal 2SHPn

I am using RB Metal 2SHPn & RB Groove 2Hn for AP. But I am facing big problem from RB Metal 2SHPn. Where RB Groove 2Hn has signal fo 60dbi , In that place RB Metal 2SHPn has 35dbi to 40 dbi & the signal is always very up down. The configuration is same as RB Groove 2Hn. So please help me.
signal.jpg
Interface_wlan1.jpg
Interface.jpg

The screenshot doesn’t show any wireless settings. Please show us your registration table and configuration screens

I had added some screen shots. Please help me
firewall.jpg

Please upgrade the RouterOS to v6.7 and then please do a wireless interface configuration reset. You can do that by clicking on the Reset-Configuration button in the Wireless interface. Then reconfigure the wireless interface with only the necessary values.

I had upgraded the RouterOS to v6.7 , The result is till good but signal is very Up Down.