Most off the shelf routers don't have the processing power to handle a gigabit connection. If they gave you a router, it can probably handle the connection, but it may need a firmware update. You'll have to contact their support for that, though, since you'r renting it from them.
I prefer to use a PC router with pfsense or opnsense. It gives me control over everything that goes in and out, and I can be sure it can handle the job. My current one is an AMD A4-5300, but I'm working on a VM router now. I should be able to switch over to it some time next week, if all my hardware works. I know it's far more secure than one owned by someone else, as my ISP wouldn't have any backdoors to my router this way, and certainly far more secure than any off the shelf router. You may want to look into it.