I have my client\'s domain registered via 1and1.com
To connect the domain to the Firebase hosting, Firebase asks me to add TWO A records with 2 IPs. In 1and1 w
I set up in the same way a website (https://lasi17.snola.es/) and it seems to work with only one A record pointing out to the Firebase IP.
In my case, I just changed the option in Hosting -> Domains -> Your custom domain (in my case lasi17.snola.es) -> Process traffic in this domain ("Edit" under the kebab menu). After that, the domain works as usual with only one A record configured.