Are we talking computers using ethernet cables or wifi? If wifi, what distances to the router, and what frequency (2.4ghz or 5ghz)?
A really common issue right now is people getting good signal strength, but poor quality wifi connections on 2.4ghz due to lots of interference. There's some tweaks you can do to improve it, but expect lower wifi distances these days than you got years past in that band.
Top tips to get better wifi distance and avoid connection breaks:
1) Lock your wifi access point or router 2.4ghz channel, don't let it auto select. In today's jam packed environment they start playing games hopping around and that leads to broken connections.
2) If you have channel bonding (where it uses 2 channels in 2.4 ghz instead of 1), turn that off. Yes, it theoretically gives you double the speed, however, due to the radio frequency pollution we have nowadays, you've got a much better chance of a clean signal (giving more distance and a faster more reliable connection) using just 1.
3) Switch everything to 5ghz that you can if you are able. MUCH more room up in the 5ghz band and it can be more effective even though those signals lose strength faster over distance/through walls.
Special side notes: Google won't even talk to you about Chromecast connection issues if it's more than 10 feet away from a router or access point, so that should tell you something about expected range these days! My rule of thumb is to add an AP (ideally mesh, but for our small home I just run my router on 2.4ghz on one side of the house and a Netgear extender configured as an AP on 5ghz for the other end of the house) for every 2-3 walls 2.4 ghz has to go through or 1-2 walls for 5ghz.
