WIFI Extender providing half speed over Ethernet

single and dual band extenders by their very nature cut throughput speeds 50% of the speed they're getting. Reason this happens is they have to use the same wireless chip to go router----->extender and then extender------>devices    and they can't do both at once. You also have to keep in mind that they aren't right next to the router so they're not getting full speed to start with. So your speeds are usually under that 50%. 

That was the whole purpose of triband extenders. They use a dedicated 5ghz chip just for router----->extender communication. The other 2.4ghz and 5ghz are for communication to devices.  

So standard extenders work great if you need additional coverage in dead spots or to extend the coverage to an area without coverage. But if you've already got coverage from the router, standard extenders aren't going to increase the speed unless you're on that boundary between a little coverage and none.