In scenario 1, the server is technically a router between the 11 and the 10 subnet. There is a sysctl that enables forwarding (i’m on the phone and can’t look it up right now). This must be enabled.

In your second scenario, the server appears to regard its subnet 11 address as just another address it has and replies.

Before using wrong a plural in a language you don’t know, just use an anglized plural, octopuses (or octopusses).

Afaik, octopodi would be correct as 'pus is actually derived from ancient greek “pous” meaning foot (latin would be “pes”). And even in Latin, not everything ending on -us has -i as plural.