Problems accessing with non-1500 mtu connection

Fabian Bläse fabian at
Tue Apr 30 14:12:34 BST 2019

Hi there,

I'm having trouble accessing with internet connections with a smaller than 1500 MTU.
This affects IPv6 as well as IPv4.

It looks like ICMP(v6) Packet too big message are sent by the routers but are ignored by your servers.

pings with payload exceeding maximum packet size (1500 ping payload) on a 1500 mtu connections work (local fragmentation seems to be working).
However when trying the same on a 1492 MTU connection (or smaller), fragmented pings get sent, however I only receive the second (smaller) fragment. The first packet is too big to fit the connection, therefore a Packet too big icmp message is sent (which seems to be ignored).

I've tried various different connections (with routers from completely different nets issuing those icmp errors) with no success.

I've attached a tcpdump from a router sitting right behind the machine issuing those icmp errors.

I would appreciate if you could take a look into this.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: kde-icmp.pcap
Type: application/vnd.tcpdump.pcap
Size: 9320 bytes
Desc: not available
URL: <>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: OpenPGP digital signature
URL: <>

More information about the kde-www mailing list