Hey there @marcA. At this current stage, Fetch TV boxes are unable to connect to our B818 Home Wireless modems, as Fetch isn't supported on our 4G Network, unfortunately. Apologies for the troubles that this may cause and let us know if you have any other questions on this regard.
Really disappointed about this since Optus cannot get me connected to the NBN until the end of February. Optus offered me B818 modem to use in the interim without informing me that I would not be able to use my fetch tv box. Also interesting that Optus is still happy to charge me for Fetch TV service