is it legal for a person to enter my fenced in property to serve me a restraining order ?

Yes, it is. Trespassing rules do not include people lawfully serving you legal papers.

I think you should be more worried about the restraining order, which can keep you from getting jobs, rather than harassing the messenger.

A restraining order is issued by the courts and is usually served by a person of the law. As far as I know he doesn't need permission to enter your property to serve it. He would need permission to enter your house if you didn't come to the door. My advice is except it and obey it are your asking for bigger trouble.

I don't know what state you're in, but in my state, restraining orders are served by local law enforcement (to prevent civilians from being shot while serving, of course.) If your state permits civilian service of restraining orders, then the "server" is able to come onto your property to personally serve you.

Yes, the restraining order is legal and you had best obey it. I suppose you could call the cops and complainabout someone invading your privacy to deliver the restraining order.

It is legal. How can you expect to receive deliveries, mail, etc. It is only trespassing if someone is there for a wrongful purpose, someone who does not have any business being there.