Ok,
I used a terminal screen to ping my gateway 44.60.44.1 while connected
to the AMPR_VPN using OpenVPN Connect for Android.
I received the following messages:
From 44.139.11.1 icmp_seq=1 Frag needed and DF set (mtu = 552)
...
and
From 44.139.11.1 icmp_seq=1 Frag needed and DF set (mtu = 0)
...
(I'm only sending 84 bytes).
-KB3VWG