diff --git a/doc/man-sections/vpn-network-options.rst b/doc/man-sections/vpn-network-options.rst
index 9a09aef8b..1dda4912d 100644
--- a/doc/man-sections/vpn-network-options.rst
+++ b/doc/man-sections/vpn-network-options.rst
@@ -525,11 +525,18 @@ routing.
   OpenVPN requires that packets on the control and data channels be sent
   unfragmented.
 
-  MTU problems often manifest themselves as connections which hang during
-  periods of active usage.
-
-  It's best to use the ``--fragment`` and/or ``--mssfix`` options to deal
-  with MTU sizing issues.
+  A VPN protocol like OpenVPN adds encapsulation overhead in each packet. If a
+  VPN packet with the encapsulation becomes larger than the transport network
+  MTU (typically 1500 or 1492) the packet will become fragmented or completely
+  dropped. These problems can manifest themselves as connections which hang
+  during periods of active usage or slower performance. To avoid these problems
+  it is generally advisable to set the tun MTU small enough to avoid these
+  problems. The default of 1420 is chosen to be safe with default parameters
+  and a (transport) network MTU of 1492.
+
+  If lowering the tun MTU to avoid MTU related problems (e.g. when tap is used
+  and an MTU of 1500 is required), the ``--fragment`` and/or ``--mssfix``
+  options can be also used to deal with MTU sizing issues.
 
   Note: Depending on the platform, the operating system allows to receive
   packets larger than ``tun-mtu`` (e.g. Linux and FreeBSD) but other platforms
diff --git a/src/openvpn/options.c b/src/openvpn/options.c
index f162b0b41..d87c6595c 100644
--- a/src/openvpn/options.c
+++ b/src/openvpn/options.c
@@ -3032,6 +3032,16 @@ options_postprocess_mutate_ce(struct options *o, struct connection_entry *ce)
         if (!ce->tun_mtu_defined && !ce->link_mtu_defined)
         {
             ce->tun_mtu_defined = true;
+            if (o->mode == MODE_SERVER && dev != DEV_TYPE_TAP)
+            {
+                /* If we are running in P2MP mode we default to a MTU
+                 * that is low enough by default to fit into a 1492
+                 * MTU UDP IPv6 packet:
+                 *
+                 */
+                ce->tun_mtu = frame_calculate_default_mtu(o);
+                ce->occ_mtu = TUN_MTU_DEFAULT;
+            }
         }
         if ((dev == DEV_TYPE_TAP) && !ce->tun_mtu_extra_defined)
         {