Sometimes it's just the result of having shitty wifi hardware. Thankfully, it's pretty easy to test. Is it only one device that keeps getting disconnected, like only your laptop but not your TV or phone or anything else?
If so, get some cheap USB wifi adapter and see if that's any better. If it is, you can try to upgrade your laptop's internal wifi card to something better (or keep using the USB one). Some of the cheaper ones that come with budget laptops are just... bad.
Otherwise, if it's multiple things disconnecting all the time, it's your router. Try a different one, or ask your ISP to give you another model if you're renting yours together with your modem.
Regular wifi should be able to handle congestion no problem. That's what the channels are for, and any half-decent hardware should be able to handle home use OK. I do all that at home without losing connection. Sure, it slows down once the bandwidth is saturated, but nothing gets disconnected altogether.
One thing to watch out for, though... are you using 2.4 GHz for your connections? If so and you're near a microwave or an old-fashioned cordless phone (for landlines), those can interfere with wifi. 5 GHz is less noisy but doesn't have as much range, and can't penetrate walls and floors as well.
@solardev: thank you so much for taking time to reply, im gonna try all that you have mentioned.