I have an old Snap era FRITZ!Box 7390 that seems to be fine on 200/10, but will this be OK on 900/400 ?

My main PCs will be connected via ethernet or UniFi, so I am not concerned with the wifi performance of the 7390, just if will be able to 'handle the jandal' or if I need to upgrade.

The 2degrees "things you need to know" page at https://secure.2degreesbroadband.co.nz/change-plan/connection  says:

• To get the best possible performance with 2degrees Ultra-fast Fibre, we recommend:
• Using a high-spec modem, such as a 2degrees Modem (model 7490)