BigBlue1
Veteran Member
This. ^^Obstructions will cause dropouts, and therefore speed degradation; how long will depend on the size and thickness of the obstruction. Obviously, higher is better, and locating the antenna so that it "looks" across the open space to the northeast from the southwest corner is likely to do the best, unless his house has a high roof line.
The app works great at finding obstructions, and for choosing a site. Your neighbor can use the app without an account.
My two cents for your neighbor is to get Starlink, and if obstructions turn out to be an issue, to go for a ham radio type tower (e.g. Rohn). With people pulling down their broadcast TV antennas, you can often find an inexpensive one used via a local ham radio group or Craigslist. I have seen them free for the disassembly around here. If your neighbor is lucky, he has exposed bedrock and can bolt the antenna to rock.
All the best,
Peter
Whether the dropouts from the obstructions will meaningfully impact use is dependent upon the type of Internet use. Some connectivity is resilient to drops. If you're loading web pages it may just stop loading for a brief time. If you're doing something that can buffer, like streaming video, then it may not cause much noticeable disruption. But if you do something like WebEx/Teams/Zoom meetings which rely on continual data transfer then it may be very disruptive to the audio and video.