Can't log into airport extreme but internet still working

This is an intermittent problem and seems to happen once a week or so and it's really annoying. Without warning, I would loose connectivity to my HDD connected to my airport extreme being used as network storage but the internet continues to work with no issues. When this happens, both my machines are affected, a MBP and MacMini. All devices, including xbox, apple tv, mobile devices will continue connect to internet and there is no affect on internet speed. Rebooting will resolve this problem.

Setup

- 6th generation Airport Extreme, software up to date

- Mac Mini and MBP both running El Capitan and up to date and various mobile devices

- I have two Airport Express, both used to stream music and used as network extender

When this happens, Airport Utility still sees the Airport Extreme but will ask for password but when I enter the password, it thinks then does nothing. Both the Airport Express do not have this problem, I can log into them with no problems so it is isolated to the Extreme. I decided to go directly via LAN cable and again, I still get internet but no go on trying to log into the Extreme and I still do not have access to my network HDDs.

The Network drives still show up in my Finder but it will not connect, will give error when trying to log in as it can't find it. I have yet to reboot this time but rebooting has always solved the problem. I've been very frustrated overall with what Apple has done or not done with the multiple issues I have had with networking and wi-fi issues the past couple years...every time I resolve one issue, something else pops up and this is the latest to bug the crap out of me. I've gone through the wi-if disconnects, shared name duplication which caused havoc with my iTunes and network including TM backups...I've had to entire reset and everything and started over several months ago and now this issue.

Any advice would greatly be appreciated.

Thanks

Dave