Public bug reported: After upgrading 14.04 to 16.04 I couldn't send big emails with attachments, I couldn't use google drive. Sometimes lowering the MTU worked.
I was able to get uploading of large files working again by playing with MTU probing and discovery: echo 1 > /proc/sys/net/ipv4/tcp_mtu_probing echo 1024 > /proc/sys/net/ipv4/tcp_base_mss Basic MTU related issues should be setup by default, perhaps interfaces need to updated during upgrade? Ubuntu 4.4.0-21.37-generic 4.4.6 Without enabling tcp_mtu_probling I couldn't upload large files over HTTPS and SMTP w/ TLS. ** Affects: linux (Ubuntu) Importance: Undecided Status: New ** Attachment added: "sudo lspci -vnvn > lspci-vnvn.log" https://bugs.launchpad.net/bugs/1574933/+attachment/4647337/+files/lspci-vnvn.log -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1574933 Title: Big uploads blocked when upgrading from 14.04 to 16.04 -- TCP MTU Discovery not properly set. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1574933/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs