On 07/08/2020 19:31, Brandon Long via mailop wrote:
Anyways, the point of my story is that it may not be a change to Outlook at all, but a Windows networking change or maybe just more network flakiness among your customers or even your own network (less likely).
I wonder if the original poster by any chance has ICMP type 3 blocked in the firewall on the server end. I seem to be coming across more `connectivity` problems and sites that don't work with lower MTUs.
Do you think that there is any chance the connection is managing the TLS and login with short packets, and then it hangs as soon as tries to move real data?
Problems tend to appear if they have IPv6 and the customer's mobile network supports IPv6. Because blocking ICMP in IPv6 is just asking for trouble.
Or the site doesn't have IPv6 and the customer's mobile network now uses 464xlat which _sometimes_ causes MTU issues, I think.
There is more of this going on because the eyeball networks (particularly mobile) are out of nat capacity so trying to save costs and add capacity by adding IPv6. (which means IPv4 is inside the IPv6).
(I'm big fan of IPv6. But when people decide they want to block ping, and so firewall all ICMP, they need sending back to networking school)
-- Tim Bray Huddersfield, GB t...@kooky.org _______________________________________________ mailop mailing list mailop@mailop.org https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
