@Jimy3000 

Have you tried turning WPS off in your router settings..worked for me.

@Jimy3000 

Did you find any solution for the light issue.

Today I got my RE 300 V1 Mesh tech version from AMAZON, same think 2.4ghz light is not working but can see the connection in available networks, did a long chat with support staff but she was not able to figure out why its not working either, I think its firmware issue and TP link knows about this but don't have any solution with them, as per support team member if its connecting to your device than 2.4ghz network is working, doesn't matter light is on or off on extender, which doesn't make sense for me at all. Light should be on otherwise this extender is faulty.

Any way the solution I been provided by TP Link is that reset your extender, play around, turn on illumination in settings, also change the SSID name to something different to differentiate original connection name (like add Extender at the end) than connect any wireless device with the 2.4ghz extender connection, I will try to connect my security camera outside, if it works i will keep this extender otherwise will return it back.

@Jimy3000 

I see tje same issue with my RE205 router. As per their manual, the 2.4/5 Ghz LED only shows which frequency band of the router it is connected to. So I guess if your router and extender connects via 5Ghz band, then the 2.4Ghz will be off. So this is expected, 

If you want to see signal strength, the signal's LED will show that.