The crux of the issue seems to be the use of privileged ports, which are (and should be) blocked by network ACL in our environment:
The functional server instance is using a non-privileged port 56242: tcp 0 0 10.99.19.46:56242 10.99.16.151:2049 ESTABLISHED The non-functional server is trying to use a privileged port 978: 116 27.617188 10.99.19.43 10.99.16.151 TCP 76 978 → 2049 [SYN] Seq=0 Win=62727 Len=0 MSS=8961 SACK_PERM=1 TSval=906311050 TSecr=0 WS=128 As a result, the non-working server is unable to establish a connection with EFS to mount. This behaviour happens with this kernel version (https://launchpad.net/ubuntu/+source/linux-aws/5.4.0-1057.60 only so far): It appears that this kernel ignores the "noresvport" mount option. ** Tags added: kernel-bug ** Tags added: bionic -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1946032 Title: NFS client fails to mount with timeout on kernel 5.4.0-1057-aws To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-aws-5.4/+bug/1946032/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
