Yeah, it can for sure. Definitely worth mentioning. Gotta watch what interface is set as the default router, or you’re bound to have a bad time. That said, the same is true with his originally proposed solution of pushing a trunk port to the VM, so it’s not any worse in that regard.
But yeah, full agreement on the correct solution. Keep it simple.
I wouldn’t let every VM have an interface into your management network, regardless of how you implement this. Your management network should be segregated with the ability to route to all the other VLANs with an appropriate firewall setup that only allows “related/established” connections back into it.
As for your services, having them on separate VLANs is fine, but it seems like you would benefit from having a reverse proxy to forward things to the appropriate VLAN, to reduce your management overhead.
But in general, having multiple interfaces per VM is fine. There shouldn’t be any performance hit or anything. But remember that if you have a compromised VM, it’ll be on any networks you give it an interface in, so minimizing that is key for security purposes. Ideally it would live in a VLAN that only has Internet access and/or direct access to your reverse proxy.
I’d rule out k8s if you’re looking for simple administration.
Not to state the obvious one, but there’s always the Raspberry Pi.
The supply has gotten better on those, so you can probably pick one up in your price range, and the power draw is super minimal.
I loved FFSend. When it died, I ended up standing up a GOKAPI server, as it was the closest alternative I could find at the time: https://github.com/Forceu/Gokapi
Definitely not as nice as FFSend though. I may have to give that fork a try instead.