A bit confused what you mean..
Every Mac has airport utility.. it is just software.. every iOS device since v7 also has it available.. so having airport utility is meaningless.. do you mean you have an airport express?? If so which model?
What is a power line adapter?
https://en.wikipedia.org/wiki/Power-line_communication
https://www.smallnetbuilder.com/basics/lanwan-basics/32768-smallnetbuilders-powe rline-faq-2015
You go to any large computer store and ask for what model AV500 powerline adapters they have in stock.
You can also google for reviews of the various models.. eg. smallnetbuilder have a number of reviews of standard models.
https://www.smallnetbuilder.com/tools/charts/powerline/view
Powerline adapters send ethernet over your AC power wiring.
They are pretty much plug in and forget.. they work without needing any configuration at all..
Cost maybe $50 for a pair of reasonable units.. bit less for the cheapie.
Wireless repeater is the worst possible way to extend LAN in your house.. it is going to be double slow.. and the express are really base end devices with slowest speeds.