5ghz wireless doesn't appear anymore and red led on 5th port

Hello there!
I used to have two wifi set on my router, 2.4ghz and 5.0ghz. They both were working just fine but suddenly I can’t find the 5.0ghz from any device anymore (computers, smartphones or smartvs). Also, I noticed that led on 5th por is always red although there’s nothing plugged on it.

Is my router physically damaged or there’s anything I could do to make 5.0ghz be conectable again?

Thank you in advance!

The solid red color is your 5Ghz link activity. The 2.4Ghz signal is most likely stronger so your devices have most likely connected to that.