ipads have wifi troubles

Recently two ipads which had worked well before, have started to drop off their wi-fi connections in my house.

Before, this never happened. But starting a few days ago, both started to lose connections, and sometimes fail to reconnect when I log into the nework.

Now this seemed to start when I installed the beta version of Yosemite, 10.10.3 on one of my two desktop macs. Both MACs, and my wireless printer, worked fine, but the iPads started to cause trouble.

I have regressed that one iMac back to 10.10.2 and the problem is partially solved. That is, the time between lost connections is increased. But it still happens, especially when one of the ipads is in the part of the house a bit far from the Airport Extreme.

Am I encountering the 'wireless trouble' that have plagues others since the advent of 10.10? Is there still a set of users having this type of problem?

Anything i can do to fix it? before installing that Yosemite beta, I had zero problems with my wireless.