I also see that you have enabled IO/APIC and that is not really necessary for a 32-bit guest which may cause an issue but I don't know if it would affect the network.
From what I get this used to work with an older version, correct?
Some things you can try.
- 1) revert back a version or two and see if it works.
2) install a second guest ( as a test ) to see if it has the same issues. That would tell us if it is the guest or something else. ( be sure to use the defaults )