When I turn on my Raspberry with the Edimax EW-7811Un plugged in, I get very slow internet (about 200kb/s). But if I boot up my Pi without the dongle and then plug it in after the startup, I get the maximum available download rate in my network (about 10mb/s).
I used another Wifi-Dongle from a friend (Samsung WIS09ABGN2), and everything worked perfectly. Also if I start my Pi with the Samsung dongle and then replace it with the Edimax one, everything works fine.
Do you have any ideas why I don't get the full speed with the Edimax dongle plugged in at startup?
I am using a RaspberryPi3 with the latest Stretch Desktop version. Using the internal Wifi is not an option, cause I need both to work.