I believe so (using allow = !all,g722,ulaw, is that what you meant?) but this seems to be a network layer issue rather than an asterisk thing. I can reproduce this same behavior just by using netcat and trying to send data back and forth, e.g. on the server side:
# netcat -u -l -p 5432
And on the client side:
dd if=/dev/zero bs=1 count=1000 2>/dev/null | base64 | netcat -u 146.235.204.128 5432
…that works fine. But if I do on the client side count=1200:
dd if=/dev/zero bs=1 count=1200 2>/dev/null | base64 | netcat -u 146.235.204.128 5432
…it does not work, and I see via wireshark on the client side that the data fragmented in the second case (but not in the first), and on the server side that it only sees the first fragment and thus does not deliver the data to netcat. Hence my question focusing on the cloud server net config. There must be folks here that have asterisk going on these (my understanding was that the ARM server is a popular entry-level option for PBX’s…) so I thought maybe they could share their ingress rules or something.
I’ve been able to google up a couple questions on the oracle forums, e.g. this, but no answers yet…