Try listening to the radio- if that works and if the AVR is connected to WiFi, can you use an ethernet cable? Your signal strength may show that it's strong, but that doesn't mean you'll have any usable speed.
Also, if you're going to reset the AVR, save your configuration, so you can load it after.
Chromecast, Airplay and MusicCast, which I would use because it works very well as long as the network connection is good, ALL need an excellent signal. If the you, your phones/tablets/AVR are on one end of the house and the router is somewhere that isn't close or if the signal is blocked by the building or heavy objects like refrigerator/heating ducts/masonry, it will never work.