Why would one of my P3's connect with my tab A tablet and my other P3 AND my P4 will not? They all connected until the latest firmware upgrade.I can connect with my iphone 6s+ and my samsung android phone, just not my tablet.

I cannot answer your question per se, but I also use a Tab A and follow this procedure to avoid connection issues; I connect the USB cable to Tab and RC, turn on RC, then turn on Tab (cold boot). Just waking the Tab up from sleep mode doesn't work for me. You have to wait after turning on the RC until the Tab lists the percentage of battery charge before you can turn it on.