WiFi signals can be disrupted by.. Baby
What I suspect could be happening is your connection to your router is busy, because it's using a popular channel.
Most routers default to channel 6 which could clash with similar routers on the same channel.
This is really easy to check if you have a mobile phone with WiFi on it. Pull down a free WiFi checker app, these can scan and show you other routers close and what channels they are using.
So you may want to change 3 channel numbers down from what your router may be set on right now.
Log into your router, look for a channel number, the range is from 1 to 12. So choose 3 up or 3 down. Save your settings, restart the router. And reconnect your devices. Monitor that and see how it goes.
The trick here is the router, you may also want to look at the log files on the router for any warnings.
Let us know how you get on.