In accessing my RT-AC66U running Merlin 378.52 via Https I get a warning from Chrome about an unverified certificate. After I agree I know it's dangerous and go on to access the router I get the Https indication at the beginning of the router URL and the logon popup comes up normally. However, after logging on the Https indication has a red line through it and a unlocked padlock appears in front of it and I am able to configure the router. This happens both locally using the local IP...
HTTPS web access from WAN
HTTPS web access from WAN