5GHz doesn't light but shows on devices

I have the same problem. The modem broadcasts dual band and the extender broadcasts both bands. However, the 5Ghz led never comes on. My first contact with Netgear said I had a bad range extender. Returned it and got another one. Had the same problem!!! When I called for support again, was told it was a hardware "GLITCH" that would be fixed. That was late October. Just today I tried to get a status on a fix and have been going round and round getting no where. Tech's want me to redo setup that I've already done multiple times. Can't seem to get to the person that said it was a "glitch" and really knows what's going on!!!