Which mean that for *some* reason the Linux kernel doesn't understand packets going out of a process, and drops them.
Timing matches:
13:15 mobrovac@deploy1001: Started deploy [restbase/deploy@38c313d]: Expose RB on both 7231 and 7233 - T223953
from SAL
While in normal situation, exposing a new port would not cause this issue, @akosiaris identified the source process to be nodejs, and temporarily rolling back this change caused the issue to stop.
Deploying the matching iptables policy didn't solve the issue.
I don't know Restbase so I can't tell if it's causing any prod issue, but it's the sign of something wrong going on (bug in restbase?) and should be addressed.