UPDATE:

The speed is back to normal (30 Mbps). It might be due to one of these reasons:

1) Another user was logged into Ubuntu (Ubuntu is sometimes known to usurp the WiFi bandwidth from other...

Device: Toshiba Satellite C55-C5241.
OS: Windows 10 x64 (Pre Installed)
ISP: Suddenlink
WiFi Router: Netgear N600 Wireless Double band router (WNDR3400v3). Firmware version V1.0.0.38_1.0.40

I...