My Win7 machines can still do networked P11/Q11 rendering just fine.  I think that Eddy has pinpointed the introduction of the problem:

Inspired_Art posted at 3:12 PM Tue, 21 September 2021 - #4427822

 Networking did work up until I believe it was Windows 10 Build 1609.. after that it was, and still is, completely broken. 

There hasn't been any recent update/change to P11 and Q11.

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5