After connecting to Philips Hue bridge for the first time it goes to Offlline after some time interm

Check the solutions of this link
https://fizz.ca/en/faq/my-modem-connected-cable-my-connection-keeps-cutting-out-how-do-i-fix

According to your post : " After doing the reset and disabling dual band and resetting the router"
.
It looks like you reset your Fizz router after disabling band steering : reset the router put the dual band back ; if this is the case then you should go back and disable band steering again.