Hi Paul,
I add that to the cmakelist and now it bypass the error

i will report later where it ends...
G:/qt6-os2/src/network/kernel/qhostinfo.cpp:413:5: error: 'sockaddr_in6' was not declared in this scope; did you mean 'sockaddr_in'?
413 | sockaddr_in6 sa6;
| ^~~~~~~~~~~~
| sockaddr_in
G:/qt6-os2/src/network/kernel/qhostinfo.cpp:425:44: error: 'sa6' was not declared in this scope; did you mean 'sa'?
425 | sa = reinterpret_cast<sockaddr *>(&sa6);
| ^~~
| sa
G:/qt6-os2/src/network/kernel/qhostinfo.cpp: In static member function 'static QHostInfo QHostInfoAgent::lookup(const QString&)':
G:/qt6-os2/src/network/kernel/qhostinfo.cpp:499:17: error: 'sockaddr_in6' was not declared in this scope; did you mean 'sockaddr_in'?
499 | sockaddr_in6 *sa6 = (sockaddr_in6 *) node->ai_addr;
| ^~~~~~~~~~~~
| sockaddr_in
G:/qt6-os2/src/network/kernel/qhostinfo.cpp:499:31: error: 'sa6' was not declared in this scope
499 | sockaddr_in6 *sa6 = (sockaddr_in6 *) node->ai_addr;
| ^~~
G:/qt6-os2/src/network/kernel/qhostinfo.cpp:499:52: error: expected primary-expression before ')' token
499 | sockaddr_in6 *sa6 = (sockaddr_in6 *) node->ai_addr;
| ^
Here it ends, will look tomorrow more as im now busy witj other things ..