Does sleep and wake work for you with a standard Linux distro? If so a newer kernel might help,like the kernel-latest-qubes-vm package, might help:
https://www.qubes-os.org/doc/managing-vm-kernels/#installing...
https://www.qubes-os.org/doc/managing-vm-kernels/#installing...
When I had similar issues in the past, I posted a question either to the mailing list or forum, and people were helpful.