Doing a wireless packet capture close to or on the AP may give you an indication what these frames are. If you don't know the source, it's hard to tell if/how this can be remediated. If you don't have the experience, probably best to work with your Aruba partner or Aruba Support.
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Herman Robers
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If you have urgent issues, always contact your Aruba partner, distributor, or Aruba TAC Support. Check
https://www.arubanetworks.com/support-services/contact-support/ for how to contact Aruba TAC. Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.
In case your problem is solved, please invest the time to post a follow-up with the information on how you solved it. Others can benefit from that.
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