Also check your bios version. I had similar problems with usb-c and fans on HP Elitebook, they were fixed with bios upgrade.
Edit: I also had troubles waking from sleep. They were caused by wwan/lte modem, I disabled it on bios and now sleep works flawlessly.
Can you access your wan ip when you are somewhere else than on your own lan?
If not, then this is probably just that your router does firewalling and nat is such order that you can access admin interface from local network via wan address.
If yes, then router has some serious misconfiguration.