It took me months to discover the cause of network instability which was making my AVR unusable. Members of this group tried to help, and those of another forum too. Finally, Marantz told me to move my router away from my TV box, even though it was the AVR which appeared to have the problem. With several metres between the router and both the TV box and the AVR, all was sweetness and light. From a network which fell over every day and took the AVR's network settings down with it to a perfectly behaved system.
I'm sharing this because I haven't seen anything written on this, so if you're having a stability problem, here's a possible cause.
Louise