WiFi signal strength suddenly reduced.

Hi.
I am not any good with networking, so I am asking here.

My WiFi router is placed at the first floor; and my entire home (two floors) was well served by it. For about a week, I was noticing that the WiFi signal strength is reducing in some rooms of the ground floor. Today I have noticed that my devices are not getting any signal in the first floor; but those are getting the signals from my neighbors properly.

Is there anything to be done from my part, or I need to call the tech from my ISP?

I know that the tech will solve the issue; but if I can do it myself with the help of my beloved fellow members, that would be cool.

Thanks a lot.

Wullail said:

it could partly be the wifi channel your router is on has now become more congested , there are apps for mobile phones that will show you the strengths of the various wifi signals , might be worth checking the signals at various points to see what channels are least used and trying to set the router channel to one of those.

Thanks! Which mobile app do you suggest?

Wullail said:

Generally though , most guides point to the best positioning for a router to be at the lowest point in a property with the signal being directed upwards , perhaps with a repeater to fill in the gaps higher up.

When the router was installed, it was checked and the best place was selected. All the issue appeared very recently.