Any Mac tech gurus on here? Need help with a remote desktop issue

The place where I work has some really old Mac Mini computers that are still running OS X 10.9.5. For the past few years, I've been able to use Google's Chrome Remote Desktop to connect from and to my work computer without any problem. Then, along comes our contracted tech help to apply the latest security updates from Apple. Now, I can still log on to outside computers but I can't log into my work computer from home or anywhere. I can't even get the server piece set up on the Mac. I've also tried several other products like TeamView, LogMeIn and NoMachine (the latter of which allows you to configure the gateway port on the router, which I thought might be tripping up all the software packages) but to no avail.

The tech company says they didn't change anything that would prevent RDP from working, and management doesn't want to pay to have someone come and troubleshoot the issue (while also acknowledging that I do need to have remote access because of my job's responsibilities).

I spoke with an RDP developer at Google who told me that RDP shouldn't have even been working when it did because Google stopped providing Chrome updates for OS X 10.9.5 some time ago. My only problem with that is then the other software like TeamView shouldn't be affected.

I've got to get this running again. I honestly don't care what the solution is. Doesn't have to be RDP. I just need to be able to access my stuff at home.

Argh! Help!