i think this works

here! http://www.tp-link.com/en/support/download/?model=TL-WPA281KIT&version=V1#tbl_b

Use Guide says red means low speed. but the speed may also be affected by the powerline system in your house. perhaps plug the adapter directly to the wall socket, or different ones can solve this.

usually the utility is in a CD. have you got it?

i found this on the website. http://www.tp-link.com/en/article/?faqid=461