I have a 400mbps network but the speed test on my desktop is only 20mbps. I did the speed test on my phone, It could reach 400mbps. So I think the problem is not about my router.

I am thinking of purchasing a new wireless card. Will that work if I just change the wireless card? Which one would work for my system?? Thank you!

 

XPS 8900

Windows 10 x64

dell wireless 1801 card 802.11bgn