Hi! It sounds like you're navigating a challenging but exciting journey toward moving to Australia. Given your strong background as a Senior Network Engineer and your certifications, pursuing skilled visas like the 189 or 190 would be beneficial, especially since they often lead to permanent residency. However, the difficulties in obtaining employment letters might pose a challenge.
If you decide to consider the student visa, it's definitely a valid option. If your wife pursues a Master's degree, that could enhance her chances of securing a job and potentially contribute to your overall points for PR later on. On the other hand, if you pursue a student visa, you can also earn points while studying, making yourself more competitive for PR.
Ultimately, it may come down to which pathway aligns better with your long-term goals and what you're comfortable with in the short term. Consulting with a migration agent could also help clarify your best options and streamline the process. Good luck!