Jesse,
To improve wireless on the MC9190, click the WIFI icon in the systray. Select "Options" then "Band Selection" from the dropdown. check both 2.4Ghz and 5Ghz bands and click the "Save" button. This setting should help to mitigate competing frequencies of other machinery in the plant.
As far as the software, I do not have experience with Naurtech browser. We use Motorola's RhoElements framework which provide APIs to the MC9190s hardware, including Network. So we have the ability to manage the user experience by monitiring the network strength.
Hope this information helps!