Changed Wifi, now Nest thinks I have a heat pump, I do not

[Feedback4Me]

Same thermostat, same system, owned the home for over 6 years - no problems.  Recently changed my wifi and routers to a new mesh system.  Now, the downstairs Nest thinks I have a heat pump, and I most definitely do not.  I have AC and Gas heat - forced air.  1 setup for upstairs, 1 setup for downstairs.  Wiring is the same on both units, both Nest units are the same.  I have tried a manual reset from the base itself.

Wires = Y1 - yellow, Y2 - empty, G - green, OB - Orange, RC red, W1 - empty, W2aux - white, C - blue, * - empty, Rh - empty

Wires have not been messed with on the downstairs Nest that is having the issue.  Neither base plate has been altered since we bought the home and have lived here.

The upstairs furnace had the blower motor replaced in the last month, but the upstairs has no issues.  That is the only kind of HVAC work that has been done recently.

[Feedback4Me]

In the app, I am unable to change from heat pump mode.  Also, I tried going into pro mode on the base, but it doesn't let me select the OB as unused as another thread mentioned.

[CoolingWizard]

@Feedback4Me 

if you have a wire attached to the OB terminal you’re telling the nest thermostat that you have a heat pump because only heat pumps need to use the OB terminal. 

AC Cooling Wizard

[Feedback4Me]

If I remove that wire, it will not work at all. Should that wire go elsewhere? 

[CoolingWizard]

 Can you do me a favor and go outside and get me the make and model number off your outdoor unit. And get me the make and model number from the indoor unit.  Make sure you read the model number off the manufacturer label. 

AC Cooling Wizard

[Feedback4Me]

Outside unit is model number 25HBC530A300 (both outside units are exactly the same make & model)

The one marked "downstairs 2.5ton" Inside unit that is having the issue is Model number FX4DNF031 

The other inside unit is marked as "3 ton upstairs" and is model number FX4DNF037

Thank you so much for taking the time to help me CoolWizard - I really appreciate it!

[CoolingWizard]

@Feedback4Me 

your outdoor unit is a 2 1/2 ton carrier model heat pump. The indoor unit is a carrier coil set and can be sent from the factory with a small heat kit in it, or the contractor installed up to a 30 KW heat strips as auxiliary heat. 

so indeed you need to have the OB wire installed and we need to set the unit type to a B. 
if you wanna check out the indoor unit, I can walk you through how to open it up and inspect it

AC Cooling Wizard