Header file net/ipx.h was completely removed from the kernel source tree on 2021-08-14 due to the ipx network layer being obsolete, causing the driver build to fail since it was depended on in rtl8723bu/core/rtw_br_ext.c.
I carefully cleaned out all references to ipx in rtw_br_ext.c and the driver now builds fine, and works.
Link to removal of ipx.h in Linux Kernel source tree
Link to my quick & dirty ipx patch for RTL8723BU
Header file net/ipx.h was completely removed from the kernel source tree on 2021-08-14 due to the ipx network layer being obsolete, causing the driver build to fail since it was depended on in rtl8723bu/core/rtw_br_ext.c.
I carefully cleaned out all references to ipx in rtw_br_ext.c and the driver now builds fine, and works.
Link to removal of ipx.h in Linux Kernel source tree
Link to my quick & dirty ipx patch for RTL8723BU