Wi-Fi and Zwave are two completely different things. I don’t think your Orbi even has a Z wave radio. They operate on different frequencies.
Your smartthings hub is a plastic box that has multiple radios inside of it. It has a Z wave radio, Zigbee radio, and depending on the model it may have a Wi-Fi radio. Each is operating on a different network. Z wave repeats only for zwave, Zigbee repeats only for Zigbee, Wi-Fi I can’t help either of those and in fact might make zigbee worse.
Imagine you live in a city on the side of a big river. There is a bridge over the river. If you want to send a package to the other side, you have two choices. You can give it to someone who will drive a car over the bridge. Or you can give it to someone who will pilot a motor boat across the river.
If there’s been a big storm and some trees blew down into the river, that might make it harder for the boat to get across. But clearing the trees out of the river is not going to have any effect one way or the other on the car traffic that is going over the bridge.
Similarly, if the storm did not affect the river, but it did blow some trees down on the street leading to the bridge, clearing those trees would help the car traffic over the bridge, but it isn’t going to have any effect one way or the other on the boats going back-and-forth across the river.
Same way, if you buy a faster boat, it’s not going to make any difference to how quickly your package arrives if you are delivering that package by car.
If you buy a faster car, it’s not going to make any difference to how quickly your package arrives if you are delivering that package by boat.
That’s essentially what’s going on in your house with Wi-Fi and zwave. Improving your Wi-Fi coverage doesn’t have any affect one way or the other on how quickly the Z wave messages arrive. And adding more Z wave repeaters won’t have any effect one way or the other on how good your Wi-Fi signal is.
They are independent networks. So the Orbi WiFi mesh router has nothing to do with your Z wave lock. They can’t talk to each other, they can’t help each other.
When you ran the Z wave repair, did you get any error messages?