I also just had this problem.
I was not able to access the RaspberryPi / HifiBerry via WiFi or Ethernet.
I had to reinstall Max2Play.
Log in via Ethernet, WiFi was not working, had to set router to Channel 11 Manually.
Unsure of what caused the RaspberryPi / HifiBerry to stop being responsive.
Glad it is working again now.