The range extender mode connects to an existing WiFi network, then repeats that signal from it's location. This means it WILL be slower (it is using some itself, and there is signal degradation) but a 90% loss seems high. Couple things that might help figure it out:
1) Is the cable modem also your main wifi router?
2) What is your main wifi router?
3) How far is the Almond 2015 from your main wifi router?
4) Between the Almond 2015 and main wifi router are there any walls, HVAC ducting, major wiring or plumbing that might help block the signal?
5) If you connect your iPhone to the main router's wifi, what are the speed test results if you hold it right where the Almond 2015 would be? (Does it get similar loss there for example).