It seems a bit more stable, but not stable enough. I switched off 2 ants and keep mining with 5... Expecting an 8th miner friday...so I hope everything is sorted by then.
So, if I understand correctly, when you have 5 ants hashing, the connection to the internet is stable and stays on, when you have 6 or 7, it starts to drop?
That would indicate - I am just guessing - a limit of bandwidth imposed on your connection by your ISP (Bandwidth throttling).
So, after all, maybe not a number of devices problem. Time to call your ISP's tech support.