Adding a delay to I2C sensor run thru multiplexer

Five virtualWrites every 5 second is fine.

I suspect that the issue lies with the WiFiNINA library, as it seems you’re not the only one with this issue…

If modifying the library as suggested in that post isn’t something you’re comfortable with then you could try this library instead…

Or maybe go for a more mainstream board such as a NodeMCU or Wemos D1 Mini.

Pete.