@Cris771 Here's how to find your router IP address.Then open this IP address in your browser. If you suspect a browser issue use another browser to do that, like Mozilla or MS Edge.

@imran-shaikh Check this post.

@Ripon747 Check your router bottom sticker (details). There you should see what's the region of your firmware and router HW version. They should match with the FW file you downloaded to succeed with...

@prhandley This has been stated in the PLC FAQ - Q3.4 but as you mentioned - it may depend on individual wiring systems.

@bill-lancaster This sounds more like a powering issue. What kind of batteries you use to power the NodeMCU.

@FiGgS Here's your old thread regarding the same issue. You've stated that the issue has gone and asked the thread closed.