The default settings works for most users with high bandwidth as you have. You do not say what your problem is, but if you get short dropouts due to crowded internet connections you can increase the Jitter buffers. Jitter buffer size should always have a higher value than Jitter buffer delay. Remember that the Jitter buffer settings are controlling the recieved audio in each box. If you still got dropouts with maximum settings, you can reduce audio quality to 0 and test. If it doesn't help and the dropouts are so disturbing that you can not live with it, it's not much to do other than change Internet operator. In most cases it's better to have the same operator in both ends, it will give lower latency and less problem with dropouts etc. I assume that you have checked that nobody else in the household is occupying all bandwidth by watching live video or something.
73 de mike
