Here's what I did to eliminate buffering -- it is rare since I did this.
I have four computers and two IPTV boxes. I have a Linksys Cable/DSL router, and a Linksys 5-port switch.
I plugged the two IPTV boxes and the switch into the router. Then I plugged all of the computers into the switch.
I then went into the QoS section of my router, and gave high priority to the two ports used by the IPTV boxes.
Now the two IPTV boxes and the switch each get 1/3 of my bandwidth, and the IPTV boxes get priority on their 1/3.
I have Cox cable internet. It is generally at around 9 MB. Sometimes it slows way down. When that happens, you notice it on the computers, not on the IPTV boxes.
In other words, they rarely buffer any more, except when you first tune in a channel, and then only for a second.