I've just today swapped out the ISPs router for a HG612 in modem mode connected to pfsense firewall/router. The instructions included how to connect a third party router (although some things had to be searched for online). I'm with Utility Warehouse which I believe is TalkTalk as a provider.
You may need to lookup PPPoE, IoE, VLAN and all sorts of other stuff which your ISP supplied router just takes care of.
You may need to lookup PPPoE, IoE, VLAN and all sorts of other stuff which your ISP supplied router just takes care of.