Compatibility issue between RBR750 and EX6120

I have an Orbi RBR750 setup and I currently have a N300 extending the network that works fine no issue . I wanted to upgrade to the EX6120 to take advantage of the 5GHz and 2.4Ghz . I configure the EX6120 and that all went well I can see the two newly created SSID  only issue I have is that if I say use my iPad and connect to the newly extended network (different SSID) on the 2.4Ghz all seem to be ok I can get onto the internet no issue however when I try to connect to the 5GHz network I always get error message saying no internet if I switch back to the newly 2.4Ghz I can use the internet no issue. Any ideas it driving me round the bend . As you can see by the screenshot all seem well ? Many Thanks in advance