"cannot send invitation you can add people using an icloud account email address with home enabled"

Everything was working fine until I was told to upgrade to the new home architecture.

I have 2 phones for this both using different Apple accounts. Both accounts have home enabled and have 2fa.

Phone 1 - Primary phone - Iphone SE - 17.2.1

Phone 2 - Secondary phone - Iphone 6s - 15.8

Homepod - Updated to the latest version

After upgrading to the new home architecture last year, Phone 2 stopped working. I removed my home from Phone 2 and tried to add it again from Phone 1 but to my surprise it would mention "cannot send invitation you can add people using an icloud account email address with home enabled"

Spoke for an hour with 1st line support and all she said is that I need to upgrade to 16.3 for it to work and If I can`t upgrade I need to buy a new phone.

I sent my invite to a friend who is on the latest version and he`s managed to get it to work on his end (he`s on the latest version)

Is there anyway to go back to the previous home architecture or to make this work?