We will sure be more than glad to help you with this issue, and in order to so, could you tell us if the Intel® Dual Band Wireless-AC 7260 came installed in this computer when you bought it or was it installed later? Here are some recommendations you can try in order to improve your connection. Wireless Networking — What are the Recommended Settings for 802.11n Connectivity?
If your computer came with this card installed when you bought it, we do suggest that you get the latest drivers from your computer manufacturer support web page: Product Support | Dell US this would be the best option for the time being. Let us know later if this piece of information helped you to resolve the issue.