Don't worry, it will all be better when we go ALL DIGITAL.
Seriously, I am not familiar with your reference to "the Harmon Kardon". I don't know if that is a service that is providing you access to YouTube or if it is your sound system or whatever. But this may not be a YouTube problem. I would suggest that you contact whoever is providing your internet access and do not accept their excuses or attempts to blame it on YOUR system.
I am in the middle of a spat with my provider, Spectrum. In addition to their cable boxes, I also use several Roku devices to get streaming video to several TVs in my house. Spectrum says I can have five or six of them with no problems. But they often freeze, plain quit, or have a highly pixelated picture. All of these symptoms are an indication of insufficient bandwidth. When I challenged Spectrum on that, they said that they did not have any bandwidth problems and that it must be my router. If it was my router, then why would it work most of the time? They said I should call when this was happening. That only took about two days: this afternoon I was in the bedroom and the crystal sharp picture on that TV suddenly pixelated. I got Spectrum on the phone and said it is happening NOW. She made a quick check and said everything was OK. I persisted and she ran more tests. Then she said that there was an apparent problem. I asked WHERE? She said in the wires or something. They are coming out tomorrow. That will be fun too.
One thing that you have to realize is that the people who answer the phone at these internet service providers DO NOT KNOW WHAT THEY ARE TALKING ABOUT. They don't know how the system works and only say what they have been told to say when the complaint is "xxxxx". They do not have a clue. So, you must persist. Make them tell you HOW they know it is your equipment and not their system. They may not be able to do that, but keep insisting.
RE: my first line, above; Spectrum IS now all digital. And it is much less reliable.