Luis,
I had some problems when trying to check OTA with my NMEA4WIFI V4.1 code.
I was having problems with OTA Upload, and the progress was getting "stuck" at about 12%- 40%.
To help others - I found that the "fix" for me was to disconnect the SeaTalk (A4/B4) inputs -
With SeaTalk wires both disconnected, I was then able to OTA Update and the progress bar showed progress to 100% - after which the NMEA4WIFI restarted with the new code. (I will reconnect the SeaTalk wires later!. )
I am not sure if this affects other s/w versions, and I hope its rare, but I am adding this post so that others can try it if they have the same problem in future.
Dagnall