Doublecheck the pubkey you put on your web server, it seems to be wrong, you need to fill it in hexadecimal format

More info (just in case):

https://mynostr.space/nip05-info/

You can query how it's now in this URL:

https://btcgandalf.com/.well-known/nostr.json?name=GANDALF@BTCGandalf.com