I do not think this is a MDM issue. My understanding is that NEFilterPacketProvider and NEFilterDataProvider are guaranteed > to support TCP and UDP traffic. ICMP traffic happened to work, but was never documented. My advice here would be to open > up a bug report, since you seen a change in behavior, so that this matter can be further weighed in on by our internal teams. > Please post a the Feedback ID here also if you go this route. Optionally, you can also open a TSI with a sample project and I can do some further digging on this as well.
@meaton this is strange, as for packet filter there is no documentation whatsoever that it supports only TCP/UDP: https://developer.apple.com/documentation/networkextension/nefilterpacketprovider?language=objc
Moreover, on several lab sessions on WWDC we were answered that Packet Filter is the right solution for filtering non-TCP/UDP flows.
In any case, we have opened a support ticket: FB9847349