I'm not sure if this is just me but I can't access aetherii.com at all through any browser.
I tried google chrome and firefox. I can ping it just fine in my terminal window. I am using cloudflare's DNS service 188.8.131.52 thing... is that an issue lol?
aetherii.com doesn't exist anymore, it's been in development hell forever. You can go to the curseforge page for Aether II and join the discord however, that's where all the activity is. There's also the Gilded Games twitter you can follow for updates.
The curseforge page is here. If you want to suggest something to the Aether devs join the discord server at the bottom if you have discord, but if it's to add the Aether to the PS4 edition it's not happening, Mojang and the Aether devs don't work together and Mojang will never add the Aether.