Edit src/muuli_wdr.cpp
Change this line:
wxSpinCtrl *item33 = new wxSpinCtrl( parent, IDC_PORT, wxT("4662"), wxDefaultPosition, wxSize(100,-1), 0, 80, 65535, 4662 );
to:
wxSpinCtrl *item33 = new wxSpinCtrl( parent, IDC_PORT, wxT("4662"), wxDefaultPosition, wxSize(100,-1), 0, 22, 65535, 4662 );
and this line:
wxSpinCtrl *item36 = new wxSpinCtrl( parent, IDC_UDPPORT, wxT("4672"), wxDefaultPosition, wxSize(100,-1), 0, 1025, 65535, 4672 );
to:
wxSpinCtrl *item36 = new wxSpinCtrl( parent, IDC_UDPPORT, wxT("4672"), wxDefaultPosition, wxSize(100,-1), 0, 22, 65535, 4672 );
Obviously you have to recompile.