Back in the days of satellite TV before internet providers were around, in the spring time depending where you lived the sun would get behind the satellite and the radio waves from the sun being more intense than the satellite signal would override and drown out the signal for periods of ten minutes or so until the sun passed by the satellite. If the channels that are being gathered by IPTV are comming from a particular satellite this might be a possible reason as to why this is happening. I am only guessing that this might be the cause.