FTTP once connected , provides whatever speed profile you pay for , it’s not like any automated intervention ( reduction) is applied to aid stability, like ADSL or FTTC, if you are not getting what you pay for , and your provider has checked that you are on the correct profile ( in other words they check that your account is set up as 900Mb ) then provided your PON light is lit there isn’t much else to check, your ONT serial number is what the headend ‘uses’ to deliver the appropriate speed, so unless you and a neighbour swapped ONT’s , that’s the only way it conceivable that you could get ‘their’ speed and they get ‘your’ speed, so even someone swapping things around externally is not going to give you the wrong speed.
If your link is ‘up’ , your account is set correctly , and your ONT serial number correctly recorded for your address, the speed you pay for should be at the ONT.
Any speed test you do needs to be on a wired device and obviously capable of using Gb speeds.
You can eliminate the router ( it’s always possible the router is faulty ) as the issue by connecting directly to the ONT and setting up a PPPoE session.
What have you done to prove it’s not your own gear limiting speeds ?
