Is there a way to set up the talktalk modem (HUAWEI HG633) as a MODEM ONLY and setting up an ORBI RBK50 as the router? At the moment i seem to have the huawei as a modem/router and the orbi as a router. Sorry if this sounds basic, I'm a slight noob when it comes to stuff like this, and I hear that by setting up the modem/router that talktalk provides as a modem only can provide better speeds when using a separate router (FYI I want to use ORBI as my wifi point as the talktalk wifi connection doesn't reach to all my rooms).
Use the HG633 in its default configuration as a modem router. It does not support modem mode, so it must be the router as well, otherwise, you will have no internet access. You can disable the WiFi on the HG633 if you wish. In this other product, you will need to set this in bridge mode & disable any DHCP server within it.