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If you just bought the house and plan on being there for quite a while, investing in some networking in the home will be worth it in the long run. 

If it's brick/concrete on the interior as well, you could DIY it or hire someone to run ethernet throughout the home. (have them pull coax, too). Brick/concrete does a great job of blocking wifi signals. You bought an Orbi system that is mesh for more access points. Good thoughts, but its backhaul (the connection between the router and access points) is going to be wireless. And that wireless gets blocked by your home. That type of home is one of the hardest to get rock-solid wireless through. 

If you were renting or planning on moving soon, I'd advise powerline or Moca adapters (ethernet over coax) to get you through. But if this is a new buy and something you'll be in the long term, I'd bite the bullet to invest in ethernet run throughout the home. While expensive (much less so if you DIY), it'll help with a lot of dropped wifi and non-existent wifi and be significantly faster. The nice thing, your orbi will work with a wired backhaul and perform significantly better (on that version) with the wired backhaul. 

You can use powerline or Moca adapters. I've used moca and like them. I've found they tend to have faster performance than powerline but powerline is more convenient. If you can't run ethernet, you might need to try a mix of things to get it working decent because of the structure of your home.