Repeated failures with cheapo ThermPro
despite initial success. Small monitor has
performed well most of last 4 weeks. Signal
adequate at 100' distance to run thermometer
in house but is lost for unknown reasons now and then.

New Batteries restore for days or a week. What upgrades are reliable?

Take a look at the YoLink Smart Outdoor Temperature & Humidity Sensor

YS8005-UC

Hmmm... This looks interesting: SensorPush HTP.xw Wireless Thermometer/Hygrometer/Barometer Extreme Accuracy Water-Resistant for iPhone/Android. USA Made Indoor/Outdoor Humidity/Temperature/Pressure/Dewpoint/VPD Monitor w/Alerts

Can have multiple monitors and there's an optional WiFi gateway available so you can see the readings anywhere there's Internet connectivity.

thanks for the links gentlemen; seems there's ample alternatives to my initial ThermPro choice.

Oddly after fiddling with the in-house unit for a while then setting it down, still inert, until after breakfast, it spontaneously kicked into active readings again.

Will be checking out the alternatives in any case.