Okay, this is a fairly involved issue, so I will try to simplify as best as I can.
In short, my new Ipad Mini 5 cannot connect to an NRF52840 running the NUS peripheral ( SDK15.3, SD-140-6.1.1). The Ipad Mini 5 can successfully connect to a nrf52832 running the NUS peripheral (SDK15.3, SD-132-6.1.1).
My older IOS devices can connect to both no problem.
I can see that the GAP layer connects from the RTT with the Ipad Mini 5 and the 52840, but the Ipad Mini 5 never hits the didConnect peripheral callback and thus no GATT services discovery is performed.
I see this problem both on my custom IOS apps and the Nordic NRFConnect App on the app store.
| Device | Chip | SoftDevice | SDK | Can Connect |
| Ipad Mini 5 | 52832 | 6.1.1 | 15.3 | YES |
| Ipad Mini 5 | 52840 | 6.1.1 | 15.3 | NO |
| Ipad Mini 4 and Older IOS devices | 52832 | 6.1.1 | 15.3 | YES |
| Ipad Mini 4 and Older IOS devices | 52840 | 6.1.1 | 15.3 | YES |
My only guess is that there is some BLE setting on the nrf52840 that is telling the newer 5.0 devices something incorrect ( 2.0 mbps? Long-range?).
Any other ideas what could be going on here? Can someone test the nrf52840 example with a newer IOS 5.0 device?
This problem seems to be the same as what others are reporting with the nRF-Connect App - https://github.com/NordicSemiconductor/IOS-nRF-Connect/issues/50
