High internet speed (using LAN) on ubuntu 20.10 system, but low speed on devices (android smart phones) after connecting to ubuntu hotspot

I recently switched on to Ubuntu 20.10 from my Windows OS. I connected my laptop having Ubuntu to internet via LAN, and the speed on it is fine, ~100 Mbps. When I created hotspot on laptop to get internet on my android smartphone using wifi, I got considerable speed ~25 Mbps during first two days, and after that the speed suddenly dropped down ~0.5 Mbps, and it is almost same from then. In order to make sure that the problem resides with my laptop and not with my smartphone, I tried connecting via another android phone, but the speed on it was low as well. I tried searching on to the solutions but I didn’t get any. I don’t want to roll back to Ubuntu 18. Is there any way to fix this problem? Any help will be appreciated.

Thanks in advance.