I installed Kubuntu 21.10 which comes with pulseaudio 1:15.0+dfsg1-1ubuntu2.2. When I start paprefs all network options are greyed out. The problem seems to be, that the directory with the modules is called /usr/lib/pulse-15.0+dfsg1, but paprefs expects the modules in /usr/lib/pulse-15.0
$ strace paprefs 2>&1 |grep /lib/pulse
access("/usr/lib/pulse-15.0/modules/module-esound-protocol-tcp.so", F_OK) = -1 ENOENT (No such file or directory)
access("/usr/lib/pulse-15.0/modules/module-native-protocol-tcp.so", F_OK) = -1 ENOENT (No such file or directory)
access("/usr/lib/pulse-15.0/modules/module-zeroconf-publish.so", F_OK) = -1 ENOENT (No such file or directory)
access("/usr/lib/pulse-15.0/modules/module-zeroconf-discover.so", F_OK) = -1 ENOENT (No such file or directory)
access("/usr/lib/pulse-15.0/modules/module-raop-discover.so", F_OK) = -1 ENOENT (No such file or directory)
access("/usr/lib/pulse-15.0/modules/module-rtp-recv.so", F_OK) = -1 ENOENT (No such file or directory)
access("/usr/lib/pulse-15.0/modules/module-rtp-send.so", F_OK) = -1 ENOENT (No such file or directory)
access("/usr/lib/pulse-15.0/modules/module-rygel-media-server.so", F_OK) = -1 ENOENT (No such file or directory)
Creating a symlink /usr/lib/pulse-15.0 solves the problem
Bug still exists in Kubuntu 22.04.1 and Pulseaudio 15.99