Before the last firmware update around 2-3 weeks ago, as soon as I appeared in the camera's field of view, a notification would go off on my mobile phone. It was almost simultaneous.  

After the firmware update this stopped happening. The notification takes several seconds (30 seconds?). Long enough for any intruder to see the camera and switch it off. 

The red LED also flashes from time to time, indicating no Wi-Fi, even if the router is on Wi-Fi or there are other devices using Wi-Fi. 

I've reset the camera's reset button and it hasn't solved the problem. The router has already been replaced with a new, more advanced one. It hasn't solved the problem.

The sensitivity to people and movement is at maximum.

I use an SD card.

Wi-Fi: -39(RSSI)

Any help?