My Wilson Sleek makes data download speed WORSE

The front end of the receiver is getting overloaded and creating electrical noise. Or, the thing has become self quieting due to the location of the external antenna on the Sleek. That is, much like a howling PA system when the mic gets too close to a speaker. Can't hear the person at the mic when this happens.

I am trying to not be too technical here. I'm a telecommunications person with 40 yrs in the field.

Those signal levels are enormous in the RF world. You system will work with 1/3 of those.