Upgrading from Vyatta 6.4 to VyOS 1.1.6 flaky network

Last night I upgraded the Vyatta 6.4 on our office Dell R210 II to VyOS 1.1.6 following the instructions from http://vyos.net/wiki/Migrating_from_Vyatta. The configuration was updated by uploading it to a VyOS 1.1.6 instance on AWS, letting it make the changes (all look trivial), then cleaning up the result.

When I left it, everything seemed to work OK - the network was accessible, the VPN tunnels were up.

This morning users noticed that the office network is much slower than before the change - traceroutes didn’t show a problem but some web sites were just inaccessible or very very slow.

The frustrating thing is that nothing in the logs or the interface output (“/sbin/ifconfig”) indicated any problem.

Switching back to the Vyatta 6.4 fixed the performance issue.

How else can I investigate this? I’d really like to move away from a 3+ years old unmaintained version.