Windows 7: I'm not getting 300 mbps wireless speed.

My sister's laptop is able to get 300 mbps wireless connection from anywhere inside the house. But my computer is only able to get 120-150 mbps. Is it because of my network card?

Router is Netgear N300.

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What is your network/wifi card?

Your also in a fixed location from having a desktop while laptops are now geared to see the go anywhere connect anywhere technology in use while on the go. If the laptop is being moved around from room to room that would also explain why the "sweet spots" are being picked up on.

Your desktop on the other hand sees the antennae on the back side of the case in one spot all the time where it may not be the idea location in relartionship to the wireless router in use. In other words you need to almost park the router on top of the case to have it in the close proximately needed for an improved connection.

The card in the laptop likely is a bit more sensitive since it was intended for portable use which can also explain the better signal strength seen while the card on your desktop is the average PCI type most likely.

NetGear is usually one of the best to use over something like the Cisco Linksys wired/wireless combo router here where a second system was still not able to be added on unless hardwired! That would have allowed the use of the wireless pci and usb type adapters for working on other systems without always a need to resync everything when swapping over from one and then back to the main case.

It could be. But generally, WIFI connectivity can never be guaranteed for anyone, anywhere at anytime.
There can be times where the person next to you gets perfect connectivity all day long and you don't.
Come back next day and vice versa.
Signal Strength is not an indication of connectivity.

There could be improper settings on your system, the router or both, or could be an incompatibility with hardware.

Could be you are more susceptible to interference in the area.
Or as stated above,, could be in a bad spot.

Try deleting the WIFI profile and recreate it.

Newegg.com - NETGEAR WN111-100NAS IEEE 802.11n draft specification, IEEE 802.11b, IEEE 802.11g 2.4 GHz USB 2.0 Wireless Adapter Up to 300Mbps Wireless Data Rates Wi-Fi protected access (WPA2-PSK, WPA-PSK) Wired Equivalent Privacy &#

Of course it also depends on your isp.

When it is a situation like this, ISP will not have a part in it. This is a WIFI issue.

As I was saying signal strength is a relative part of things as far as WiFi routers go to start with. In some cases simply leaving the room with a laptop already configured fully to the best you can have it will see a dropoff! This has been one of the main complaints all along as far as wireless connectivity issues.

My network card is a PCI Realtek RTL8190 wireless N. Can't find much information abut it on google.

Does increasing the beacon interval of my network card increase the connection speed?

Not using a NetGear adapter card along with a matched router. That can throw things off.

It all depends on the setup of the hardware you have, The distance you are away from the router if both the modem and router is capable of receiving a 300mbp/s rate, It also could be your settings in the Device Manager not allowing you to access the data bandwidth speed.