I'm guessing your work email address ends in .edu?

If you're like most IT managers, you probably have a budget. Which is probably wholly inadequate for immediately and elegantly solving your problems.

Look at your company's business, and how the different offices interact with each other, and with your customers. By just upgrading existing infrastructure, you may be putting some of the money and time where it's not needed, instead of just shutting down a service or migrating it to something more modern or easier to manage. Free is not always better, unless your time has no value.

Pick a few projects to help you get a handle on the things that need more planning, and try and put out any fires as quickly as possible, without committing to a long-term technology plan for remediation.

Your objective is to make the transition as boring as possible for the end users, except for the parts where things just start to work better.