Keyboard beeps when entering password Solved

I have been using this router for several years with no issues. Apple AirPort Extreme Base Station  AC. A couple of days ago it starting giving a keyboard beep when trying to enter the fourth character of the password. Password has not changed. This happened on both a 2016 MBP and 2009 iMac. I usually have the three Macs hooked up to it at all times and am having no problems with those. One is hardwired two are wireless. The wireless are a 2008 Mac Pro and a 2010 Mac Mini.

On the customers 2009 iMac I was able to hook up via ethernet cable, it is running El Capitan. The 2016 Touchbar only has thunder ports and running High Sierra. But the beeping on the fourth character I don’t understand. It happens when trying to enter a bracket “[“. I have no idea why this would just come up out of the blue.

UPDATE 9/19/18

I had a couple of machines come in that had been on my network before from a couple of years ago. They were not set to remember the password but had no problem connecting or entering the password.