At home we recently switched to a tankless water heater and we went all out on a fancy Rinnai RUR199IN condensing tankless heater with Control-R WiFi module.
The unit itself is great! Easy install, works amazingly, fantastic instructions, etc. The Control-R WiFi module though? WOW - that's some trash!
The main problem I had was getting the damn thing to stay on the WiFi network. I ended up with a blinking or solid purple light every time. I tried everything and resigned myself to the fact that I'd probably have to call support when I tried one last thing - and it worked.
Here's what didn't work:
- Shouting and cursing
- Searching for other solutions online
- Disabling my Pi-Hole
- Changing network settings, checking firewall ports
- Allowing full access to my network
- Creating a dedicated, unauthenticated 2.4GHz WiFi network to test
- Praying to jeebus
- Resetting the module like 100x
Here's what did work:
I created a new 2.4GHz WiFi network (I'm using TP-Link APs with their EAP Controller software), applied the same policy I apply for all IoT-only networks which allows internet, but no local LAN access (other than the pi-hole DNS server), and selected "TKIP" for encryption rather than "auto" or "AES". THAT WAS IT!
Seriously - there's obviously a bug in the WiFi module that can't actually use AES encryption and it needs to be forced to a TKIP-only system. Annoying, but given that this will be the only thing on this network in my house and I can now restrict that network to just that MAC address, I'll consider it 'safe enough' to not really care about. ...frustrating though!
TL;DR
The Control-R WiFi module only works with TKIP encryption. It's stupid and Rinnai should feel bad about this.
I recommend putting it on a dedicated 2.4GHz network as I noticed they have an 'alternate setup page' that uses http (yeah, no TLS) and it asks for your WiFi password. Clearly, security isn't a priority for Rinnai :-S
