USB 802.11n adapters have small antennas. Use a to lift the adapter away from the PC case (which acts as a Faraday cage). Place it higher and closer to your router.
The Critical Role of the Intex 802.11n WLAN Adapter Driver In the landscape of modern networking, a hardware device is only as effective as the software that controls it. The Intex 802.11n WLAN adapter intex 80211n wlan adapter driver
Since Intex rarely updates drivers, you should identify the chipset: USB 802