Can you tell us which broker you're using ?. In my experience connection interrupts on broker's demo plat form
if the problem is another you should buy new net connection
i have the same problem in past the reason was my wireless connection wasn't suitable for online trading
i solved it after change my internet connecting using cable internet
have the same issue,(i think so)- ICMarkets demo on forexVPS ,it freezes every (almost ) hour for few minutes , mostly cca 6 min after full hour...but after all I think it works in backstage but screen and watch is freezed!