At a guess, I would say that your provider is the issue not your box. Your internet speed is more than enough to cope with streaming.
Are you using a wifi dongle or going through an ethernet cable? I would always suggest the latter. See if this eliminates the freezing.
I have a h.2s and it performs quite well. Not as powerful as going through a smart tv or even a MAG box due to their processsing capabilities but IPTV generally works... depending on your provider and which server they use. If your provider is a reseller, they could have sold you the same sub to say another 1000 other members all using that same server at the same time. That is when you will find that the server may not be able to cope with the demand, thus slowing down, pixelating or even freezing the channel you are viewing.
Personally, if I were you, I would request a few free trials for your h.2s on here. Make sure you opt for those providers who are not resellers, who perhaps even own their own server(s). This should give you a clearer picture (no pun intended!) of what your h.2s can or cannot do. If you find that it is still struggling to perform even with a new IPTV sub, hate to say this but you may have a clone. They look exactly the same as the genuine item... except the components inside!
Just hold fire on buying a new IPTV box yet. My dad has just bought a new MAG 256 box. The picture quality is exceptional but...
... even that occasionally freezes, especially on HD channels! I have suggested a few new trials to him too!
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