Static IP no longer active? WAN IP not as expected.

[SilverBT]

For various reasons we've moved to a 3rd party router (TP link AC2800). We have BT Business Infinity with a static IP.

We've connected just fine to the DSL, but as a result our WAN IP address is no longer the reserved static IP address.  It changes on each connection.

There is an option to set a static IP (which i've read shouldn't be set on various posts), and of course that doesn't then connect.

Is there something we are missing? Is the static IP only configured for the hub provided, or should 3rd party routers be able to utilise the provided static IP?

[SilverBT · Accepted solution]

SOLVED: For the record (and if anyone else is silly enough to find the same problem) - make sure you use your BT business network username and password - not the residential one! When I logged back in to the smart hub I could clearly see the correct credentials!