I have the same problem on two windows computers and my iPad. I tried on my Chromebook and was able to get in.

I found a work around for not being able to update main router. 
 

first update satellite routers by using their IP addresses 

Set one of the satellite unit as the primary unit

then access the primary deco which is now a satellite using its ip address

 

once done, reboot all of them. 

  @Jetdrive 

I worked with TP-Link support for a couple of nights and they were able to fix the problem with the satellites going offline and not being able to login via the web interface. Version 1.1.6 fixed both of these problems and should be available soon. 

Jetdrive wrote

  @Jetdrive 

I worked with TP-Link support for a couple of nights and they were able to fix the problem with the satellites going offline and not being able to login via the web interface. Version 1.1.6 fixed both of these problems and should be available soon. 

  @Jetdrive thanks for the info. At this point I'm just going to pass on the 1.1.5 and hold out for 1.1.6. 

  @Jetdrive 

 

Thank you. I appreciate you investing your time doing this.