IPv4 is working? Got any public IPv4 address? For the IPv6, please share screenshots of the Ipv6 status and configuration.

Try http://192.168.0.1, if it doesn't work, use another browser. Make sure your computer does not connect to any other networks besides tplink. You can also try on your phone.

How do you FTP to the disk? You set parental control so only the client in the whitelist can access the disk? Does it really work by putting IP address in the keyword box? I thought it's only for...

It's either whitelist or blacklist.

Your bulb has the latest firmware? If this keeps happening, I think it's better contact tplink support directly.

Take a video of the bulb flickers, let the tplink support to verify it's a hardware failure or settings problem.