Mike,
I operate the IC-706 over a NC to Chicago Internet link. Two different cable ISPs (Comcast and Time-Warner).
I found that most of my packet dropouts were in my LAN. I had a lot of luck solving this problem by giving my radio data PREMIUM priority in the router and changing all other traffic to STANDARD. Do this in the router QoS settings, especially at the radio end. I was getting dropouts even with nearly zero traffic on the LAN.
I still get an occasional dropout, probably ISP related, and buffer settings helped a bit there too.
Incidentally, I had the same problem with my "MAGIC JACK" VoIP connection. QoS settings fixed that too.
73,
Fred
WA9MVZ