Signal of router is not too good which i expected

I would suggest you create a service ticket and have the channels up by technicians mentioning the wifi signal strength. They would do this remotely. Sometimes the channels are not correctly configured.
 
I suggest you to use a different router by connecting it to Nokia router, and disable Wireless on the Nokia router.
Those are the worst,
For me they just act as Fiber to Copper converter...
 
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