Unable to open websites despite internet working correctly

I'm facing the following problem lately: I'm working on a Windows 10 machine connected via Wi-Fi to my home modem where other 4 devices (a XP old PC via cable and a W8.1 notebook, an Android phone and an Android Tablet) are also connected.

All devices are connecting and using the Internet properly with the exception of my machine. The wireless have being constantly falling probably thanks to the W10 or its relationship with my Wi-Fi adapter, but when that used to happen the entire Internet went down for a couple of minutes only to go back full force later. During this period the entire web was unnaccessable by all means.

But lately another problem appeared: some times I'm unable to load any page on the web by any browser while Windows report that the wireless is OK and BitTorrent continues to both upload and download data normally! When this happens the browsers (Chrome and Firefox) report ERR_CONNECTION_CLOSED or timeout or any common message of being unable to connect to the server. As I write this the connection once again went down while BitTorrent is downloading at 600 kbps!

I reset the modem lots of times, used the Windows problem solver with no results, and now I'm without ideas of what to do. Any help would be appreciated.

NOTE:

The problem started appearing during a failed attempt to change the Internet from 10 to 15 Mpbs. During this time the provider noticed there was an error with the system: it was already sending 15 Mpbs to my home while the proper new modem wasn't installed. During the internet stop working for all devices. But the problem was fixed and all other devices returned to their normall function with the exception of my PC. Could it be that this somehow damaged my wireless adapter?