Make sure your WiFi is on different channels and the neighbor's network won't be a problem.
Download Inssider and look at his signal strength- if it's in the -75dB range, don't worry about it unless yours is also in that range. If yours can't over-power his, something is wrong.
Like all high frequency RF, 5Gig doesn't go as far or pass through building materials very well. How far apart are the houses? At most, I would think only two of his devices would affect your network and even then, only if they're extremely close and the materials stop nothing. If you have room between the houses, plant a short tree- RF doesn't go through water very well.
All of this is why I hate the advertisements of "WiFi works everywhere" BS.