You're not the only one. I'm having the same issue here too. Freezing every 15 seconds on every channel my dad & I watch normally. (CNN, Fox News, Discovery, Discovery Turbo, TBS, TNT, & FX. Haven't checked any foreign channels)
I've been using the service fine for over half a year, but then all of the sudden this week all our channels are unwatchable.
ISP hasn't changed, nothing in our network configuration has changed, haven't changed anything on Kodi, & I tried connecting my device over both wi-fi & ethernet - both with the same freezing. Doesn't seem to matter what time of day, peak time or not.
I've tried reseting all my network devices (modem, router, switches, etc.), "reseting IPTV" on the donation check website, and changing MAC.
I'm using an Nvidia Shield, Kodi 16.0, PVR Stalker 1.0.3. ISP is Time Warner Cable, US West Coast.
Currently messing around with my config and I'll let you know if I end up figuring this out. I kinda have a feeling this freezing is out of my control though.. If anyone has any suggestions please shoot.