The Nighthawk app on my iPhone iOS 16 opens with a login page. It does not accept my password. Remember Me is turned on. Router is RAXE300. No trouble logging in with routerlogin.net. I turned on Armor earlier in the day using the Nighthawk app. Later in the day Nighthawk app started showing the login page and would not take my password. Note that the password used successfully with routerlogin.net does not work with the Nighthawk app. The Nighthawk app updated on my iPhone a couple of times over the last several days.
