Unstable WiFi speed

[NoNameExe]

Hi. My wifi adaptor is a TP-Link WN951N v3.2. My modem is a Netgear DG834G.
Here is the problem :
My wifi speed is really unstable. Normally my maximum connections speed is 9.5mbps, but it is very very unstable. Sometimes the connection speed drops to 0.8mbps for a while.
When the connection speed drops I try to ping my modem using the CMD ping command. When I get heavly speed drops I notice that the ping between my pc and my modem is 200/500ms. So really high and unstable.
My other wifi devices like smartphones doesn't have problems. They works fine.
I really don't know why I'm getting this problem!

Here is what I tried to fix the problem :
-Reset my modem to factory settings
-Upgraded my modem's firmware
-To change modem's wifi channel
-Clean installation of Windows 10
-Tried both manufacter driver and windows driver
-Disabled useless settings in Windows 10 like geolocalizzation
-Disabled windows firewall

 

[mcnumpty23]

the problem with wifi cards is sometimes the metal of the pc chassis can interfere with the signal

thats why i prefer usb wifi adapters

 

[NoNameExe]

the problem with wifi cards is sometimes the metal of the pc chassis can interfere with the signal

thats why i prefer usb wifi adapters

Thanks your answer!!
I am having this problem for two months and I bought this wifi adapter 1 year ago. I don't think the problem is a interfence with my case. What can I try to confirm your assumption?

 

[Onus]

USB wifi adapters tend to have very poor antennas. PCI and PCIe adapters have better antennas, which extend outside of the case, so they are NOT shielded or blocked.
You might try re-orienting the antennas, or even temporarily move your PC. If this makes a notable difference, you may need to track down a source of intermittent interference.
I've also found that the radios in wireless cards don't last forever; it may be time for a new one.
If you have an available PCIe slot, I'd suggest http://www.newegg.com/Product/Product.aspx?Item=N82E16833704133 which appears to be a later version of one I've got. Mine was a review sample, but iirc the price was similar.

 

[mcnumpty23]

the problem with wifi cards is sometimes the metal of the pc chassis can interfere with the signal

thats why i prefer usb wifi adapters

Thanks your answer!!
I am having this problem for two months and I bought this wifi adapter 1 year ago. I don't think the problem is a interfence with my case. What can I try to confirm your assumption?

if it worked ok for 10 months then signal getting blocked by the pc case isnt likely then

possibly interference from other wifi devices--changing channels sometimes helps that sometimes doesnt

how far from the router are you and whats between it and you? ie how good a signal are you getting when its ok?

 

[mcnumpty23]

USB wifi adapters tend to have very poor antennas. PCI and PCIe adapters have better antennas, which extend outside of the case, so they are NOT shielded or blocked.
You might try re-orienting the antennas, or even temporarily move your PC. If this makes a notable difference, you may need to track down a source of intermittent interference.
I've also found that the radios in wireless cards don't last forever; it may be time for a new one.
If you have an available PCIe slot, I'd suggest http://www.newegg.com/Product/Product.aspx?Item=N82E16833704133 which appears to be a later version of one I've got. Mine was a review sample, but iirc the price was similar.

yeah sorry i wasnt clear enough-i use usb with detachable antenna so can replace it with a better antenna if needed

 

[NoNameExe]

if it worked ok for 10 months then signal getting blocked by the pc case isnt likely then

possibly interference from other wifi devices--changing channels sometimes helps that sometimes doesnt

how far from the router are you and whats between it and you? ie how good a signal are you getting when its ok?

Hi thanks for your time. I already tried to change wifi channell. The router is far about 6-7 meters. The Windows signal is 4/5 and sometimes 5/5. It is very annoying.

EDIT: There are news. I re-orented the adaptor's antennas and I found a big improvement. The antennas were near the case. I rotated the antennas to the outside from the case.
Now the antennas are like this :
http://www.ixbt.com/comm/tp_link_tlwn/tp_link_tlwn-8.jpg
The antennas orentation were like this :
http://www.itshop.pk/product_images/s/294/n2972___86126_zoom.jpg

My minimum connections speed now is of 7mbps instead of 0.8mbps. It was interference with the case? Thanks.