Wifi thermostat connectivity

[RuralDude]

I have a Carrier Infinity touch screen thermostat WiFi enabled that has been used for years, I recently added OPNsense firewall/router in between my modem and wireless router which i disabled dhcp (just turned it into a hot spot), now my thermostat doesn't connect to the servers at carrier and for the life of me i can't figure out what the hell it wants.

Nothing special in my network just simple single subnet of 10.0.0.x, however the thermostat came with its own router!  Its a TP-Link pre-configured to be used just for this thermostat, the instructions are simple and just say to plug the wifi port into your existing networks port and connect the wall unit to the wifi ssid, done!  It's also on its own subnet 192.168.127.x. 

Why would this not be able to get out of the network?  does it want a port forward?  do i need to setup some rules for cross subnet talk? do i need to setup a Vlan for the subnet it's on?

Not sure what it needs to work, any help appreciated.

I'm watching the logs and i don't see anything happening from the thermostat subnet so i'm a little lost at the moment, i can't be the first person that has done this.

[bartjsmit]

Does OPNsense have a static route for 192.168.127.0/24 via the TP-Link?

System, Routes, Configuration.

Bart...

[RuralDude]

Yes, I don't have access to the TP-Link router config, it's pre-configured from Carrier.