One thing, do you use IPV6 on your network? Roku just recently started supporting it and there have been reports of people having issues with it. I can't recall the details and I would think it would affect wired or wireless the same.
There have been very few reports of wired connections not working over the years and when they do occur it has almost always been because of a bad cable or bad Ethernet port. It seems highly unlikely that you could have three bad Ultras and if it was something in the software then we'd be hearing a lot more reports. My Ultra uses a wired connection and I haven't had any problems. It's been a long time since I've used Internet Connection Sharing on a Windows PC, but that might be a way to test one of the Ultras if you have the appropriate computer. Otherwise, I think you'd have to take one to a friend's. There's little to no Roku technical support here. Most of the moderators will just give a link to a web page or claim to forward your concern to ??? We never seem to hear anything back in those threads except maybe for people saying they never heard anything either.
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