I just checked with a my Nintendo Switch which reports or seems to report actual security mode. I connected it to both a non D-Link wifi router and the COVR-3902 and its connected to both and using AES, not TPIK:
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So at least one device reports using AES with the 3902.
I presume that there could be some mis-handling of the mode by the newer iOS version since D-Link only has the mode set for Automatic, thus letting the wireless client device determine which mode to use. Maybe the newer iOS isn't picking AES and choosing TPIK.

However, if D-Link can provide a manual UI method to force AES only, this would be helpful as well.
