Facing same issue here. Help is appreciated. 
 

I faced similar kind of issue last time

With an intuitive app, plenty of customization options, reasonable prices, and reliable equipment – all very crucial factors – we think that overall, Reolink is a great option to consider for home security.

I'm happy to see the issue is now solved. 

The slave unit may be too far away from the main router, or there are too many obstacles between the main router and slave unit, causing that the mesh connection is unstable.

Step 1: Download the latest firmware to your PC. Step 2: Extract the digicap. dav file (which is the actual firmware file) from the zipped file you downloaded. Step 6: Scroll to the bottom of the screen you'll see Upgrade Firmware.

Hardware incompatibility. Incompatibility is likely the most common cause of Wi-Fi issues. There are so many hardware vendors with lots and lots of devices. It's tough to keep all of them interoperating well in all scenarios

All you need is a correct IP camera address and type it in the web browser address bar, that's it. However, if you want to view live streaming of your IP cameras in external Internet, you need to configure IP camera port forwarding.