Going crazy here!  Installed the Archer C5400 and all working great.  Tried to log into the web interface today and it says incorrect password.  I had the username and password stored in Chrome and nothing has changed to my knowledge.  I can access it through the Tether App on iPhone so changed the password there, still can access through Tether but not the web interface.  I am using the ip address to access the web interface, get warnings of unsecured connection despite it being local side of firewall, sometimes it tries to connect to the cloud, again tries to send password via http so insecure and have to override Bitdefender.  Whatever I try I cannot get into the blasted thing and now have one attempt left before it locks me out, no idea what happens then!  If I try the suggested (google search) admin\admin combo to log in it says incorrect format, needs to be an email address as user name.  Am I going to have to reset the thing to gain access again, such a PITA that would be.