|Ok that at least confirms that it's a wifi issue - not something else...|
This does seem to be a fairly common problem with win-8.1 and assorted wifi adapters - not the least some of those in some the Dell kit..
Can you discover what the actual wifi card is - who made it and its model number?
Device Manager will give that information. Also if your run something like Belarc Advisor (a safe freebie utility to run) it will generate a complete profile of what's what in terms of hardware and software (and all the software keys too)
Also running msinfo32 from the start\run dialogue box (wherever that is is in win-8x...) will do much the same.
Once you know that actual make/model of the wifi adapter... it may be possible to find a proper driver from "their" support site.
What computers (make/model) are your friends using too - and if possible check what wifi card they are using - presumably all are running win-8.1 (or are they)?
Similarly if you go elsewhere (to use another wifi access point/service) do you have the same problem on wifi there?
Have you been into the wifi setup on your router too; checking what controls are setup - mac filtering (or not); assigned/fixed ip address for a given network adapter?
What make/model is your router (presumably an all-in-one item; not a router connected to an external modem - which in turn goes to your isp connection/service)?