You can also put in a ping option to specific the packet size. Sometimes the default small packet size will go through just fine, but larger packets will fail. So up the packet size on the test. Don't recall the letter of the option, but I "think" it might be -s followed by the size of the packet that you want to try...
so something like
ping -s 1024 would send a 1024 size packet.
Sorry, -s is the count. -l is the size. Here's a handy list of Ping commands.
Options:
-t Pings the specified host until stopped.
To see statistics and continue - Type Control-Break;
To stop - press Ctrl+C.
-a Resolve addresses to hostnames.
-n count Number of echo requests to send.
-l size Send buffer size.
-f Set Don't Fragment flag in the packet (IPv4-only).
-i TTL Time To Live.
-v TOS Type Of Service (IPv4-only. This setting has been deprecated and has no effect on the type of service field in the IP Header).
-r count Record route for count hops (IPv4-only).
-s count Timestamp for count hops (IPv4-only).
-j host-list Loose source route along host-list (IPv4-only).
-k host-list Strict source route along host-list (IPv4-only).
-w timeout Timeout in milliseconds to wait for each reply.
-R Use routing header to test reverse route also (IPv6-only).
Per RFC 5095 the use of this routing header has been deprecated. Some systems may drop echo requests if this header is used.
-S srcaddr Source address to use.
-4 Force using IPv4.
-6 Force using IPv6.