[Babel-users] Unable to ping, intermittent connectivity

[c g]

Greetings.
I have been tasked with a project to create a mesh network of raspberry pi computers for use in some testing environments here at work.  I will not pretend to be any kind of an expert on anything involving mesh networks, general networking, linux or any part of this, I am just the guy whose lap this landed on. 
I have spent a lot of time reading around and quite a bit of time experimenting, and I am having some trouble getting stability out of this system.  
At present I have 4 pi machines, though I want to expand it to a dozen or so.  Each pi is using raspbian, babeld, ahcpd, and a ralink rt5370 wifi dongle with a driver that I compiled from the source provided by mediatek. 
Sometimes everything works.  Sometimes I can bring up each pi and everyone receives both an ipv6 address and an ipv4 address through AHCPD and I can ping and communicate.  Traffic seems to be hopping from one connection to another etc.  However, inexplicably we will lose communication across part or often all of the network.  I will see all the machines in the routing table, both the ipv4 table and the ipv6 table.  I can watch nodes enter and leave as they are powered off and on.  But I lose all ability to ping or do any other kind of communication.  
I am at a loss as to why these nodes can clearly see each other and communicate enough to pass out addresses, but be unable to ping or do other kinds of communication.  
I have spent days reading everything I can find, and clearly this is a system that is working in many applications around the world, and other people aren't posting anything I can see with a similar problem.  This leads me to conclude that obviously I am doing something wrong, or failing to understand something crucial. 
If there is any assistance provided I would greatly appreciate anything pointing me in the right direction, any additional reading material I have overlooked.  
I would be happy to provide any configuration details that might be applicable, though most things are pretty close to default. 
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