TL;DR – Without dumping a bunch of money, is there a quick MacGuyver-y way to help diagnose what's causing the EMI in my house?
Longer –
I have the curse that I'm a little too technical to be helped here by dummies.com, but not sophisticated enough to have or use the tools I imagine most of you would recommend.
Several times per day – sometimes hours without issue, sometimes firing once every 5 seconds – the wifi blips for a few seconds. I've caught command line ping dropping packets for about 2-5 seconds, on computers throughout the house. Notably, we realized the baby monitor also cuts out for just a few seconds at the exact same time ping goes down.
So it would appear my house is regularly awash in brief bursts of EMI, that's causing connectivity issues (especially a problem with video conferencing in the current covid-19 lockdown world). But I have no idea what to buy or rent to help me triangulate where this is coming from or what it could be. I have some dim memory that magic things can be managed with an oscilloscope and simple length of metal plugged into it operating as an antenna.
How can I find EMI?
(Meta – if there's a better place besides electronics.stackexchange.com for this please leave a comment)
UPDATE (for more information, as requested in comments)
The Baby monitor and its receiver is an Infant Optics DXR-8, audio and video over 2.4ghz wireless (NOT wifi / tcp-ip, but some point-to-point proprietary). In fact, shielded twisted pair cat5 appears undisrupted (but not a fix for everything getting disrupted in our wifi world). The wifi is 5ghz AC + 2.4 ghz N (both ranges/protocols impacted). To my knowledge, I'm not particularly close to any unusual EM sources – e.g. airport, military base, transformers – though I guess you never truly know. It is relatively dense population (single family residences every 35 feet) – I'm wondering if a neighbor has one of these "weaponized" routers that disables other people's wifi, but need some kind of proof before I go pounding on doors. All of this aside, to keep the question within format for stackexchange, assume generic American residential suburbia, and let's see if we can dream up a gimmick that works generally. Anything further peculiar to my immediate situation I can answer in comments.
Best Answer
A yagi antenna and a cheap SDR might be good to play around with. Make sure the antenna and SDR work in the frequency range of interest (so if you want to look for wifi signals, then the antenna and SDR need to work in the 2.4GHz range.) MSI SDR is an SDR I like because it has a range of 10kHz to 2Ghz (but you need 2.4GHz). RTL-SDR shows an SDR solution for 2.4Ghz.
SDR's are software defined radios, you can download spectrum analyzers for free and see which bands are carrying radio information.
Keep in mind that you may not be able to find exactly what the source is because of reflections and attenuations of walls and other objects. The antenna could also have a lobe in the back so read up on antenna patterns (or look at the one you buy, antennas are not perfect by any means, they have different lobes and nulls which changes the gain with direction)