The Vigor 2952 features WAN connectivity via its two WAN Ethernet ports, one of which can connect to either SFP or Ethernet WAN links. The two USB ports allow for connection of up to 2 compatible 3G/4G modems for additional connectivity.
The ethernet ports can connect to DSL modems (e.g. Vigor 130), a cable modem or any other Ethernet-based Internet feed. The multiple WAN interfaces can be used either for WAN-Backup or Load Balancing. Load-balancing or failover supports IPv4 only currently (not IPv6).
WAN-Backup provides contingency (redundancy) in case of your primary Internet connection or ISP suffering temporary outage). Internet Traffic will be temporarily routed via the secondary Internet access. When normal services is restored to your primary Internet line, all traffic is switched back to that.
The USB port provides Internet connectivity (main, backup or load balanced) by connecting to a compatible USB modem (or cellphone) for access to the high speed 3G/4G/LTE cellular networks from UK providers such as Vodafone, O2, 3 and EE. If you don't have a wired Internet connection at all, the USB/3G/4G access method can be used as your primary/only Internet connection, ideal for temporary locations, mobile applications or where broadband access is not available.
Alternatively, if you will be making more regular use of 3G/4G/LTE, consider the Vigor 2862Ln model with its built-in cellular modem & SIM slot.