Santosh Welcome to the community!
The signal values of your modem are ok. We see a device which has a bad connection in the 2.4 GHz range.
I can give you the following tips:
Connect a LAN cable to the room where you have all your devices connected. After that I would connect a LAN switch bay, where you can connect all your other devices via LAN cable.
The reason I recommend LAN cabling is because there are too many WIFI signals interfering in your property. You can see here how it looks like in your case. Your modem is transmitting on channel 6. All different colors are one WIFI transmitter each in the 2.4 GHz range.