Hello   @flowmika 

Can you check if tapo bulb is still on the router client device list or if bulb is accessible when phone is connected to home wifi network when issue happens? 

If bulb is completely dropping from the wifi connection, you could try some tips here: 

1. Please confirm Tapo bulb is receiving strong Wi-Fi signal from Wi-Fi router. 
Tapo app-> Device Settings-> tap router Wi-Fi symbol->  signal strength (value of the RSSI)
(40dBm- 70dBm is good to average, less than -70dBm is relatively poor : relocate smart devices or router closer to each other)
2. Please confirm Tapo device firmware and Tapo APP version are up-to-date 
3. Ensure smart device is connected to main router directly, not through AP or extenders
4. You could try to change a different 2.4Ghz Wi-Fi channel on router and see if that helps 
5. Turn off Advanced wireless settings on router  for test like Wi-Fi Optimizing (Channel Optimizing)/ Band steering( Smart Connect )/ Mesh feature etc

If the concern persist, can you help confirm some information to locate the issue: 
1. The Router model:  
Does smart device connect to router directly or through extender nodes in a mesh system? 
2. The  frequency of the issue:
3. Can you control the Tapo  device locally (when phone connected to home Wi-Fi) when the issue happens? 
4. MAC address of the Tapo device (please share via private message)

Thank you.