That's a bit on the weird side, if the Apple TV can detect the network it should be able to connect.
Is your hub running both the 2.4Ghz and 5Ghz WiFi networks?
If so, do they both have the same name? Sometimes there's an issue with that and changing one of the networks SSID can help.
Also, I don't know which hub you have, but if it has the smart setup enabled it's worth disabling that and trying, it's been known to cause issues.
I am with BT Internet and have been running ATV3s for a few years and an ATV4 since they were released without any issues. I am not using the BT supplied Homehubs, so can't comment on that. My Internet speed is dismal, but that is another story...