My receiver is not working, it keeps saying unavailable I’ve tried resetting it up. All the entitys aren’t working too. My media controller can’t turn it on. Could you help me?
Do start by providing details…this reads alike: it-does-not-work.
What integration (there are more on Denon) and which steps to set it up?
First of all, make sure, the Denon device’s LAN connection is always up in standby mode. A lot of them have a setting in the setup menu for that, which is in factory setting OFF. 
It just says unavailable. Not many specific reasons like “it-does-not-work” display, right now on the home screen it shows, “This entity is no longer being provided by the denonavr integration. If the entity is no longer in use, delete it in settings.” In the settings under devices and services it shows, “Failed setup will try again.” 1 more thing is in the settings the denon avr receiver intergration reloads constantly and reinitalzing automatically trying to fix it self. This problem just appeared one day and just stopped working just a big stump.
does the denon app work? and have you verified the IP address is still the same?
Yes, the IP address looks the same. I haven’t been working on this problem lately.
denon mobile app work on your phone?
No, I can’t get it to work on my phone. I don’t have the denon app.
you should download and try with the denon app, which may help determine if the problem is in home assistant or if the problem is with the receiver.
1 more thing to tell you my printer said unavailable and I turned it on and all the entitys for the printer started working.