Wi-Fi speed suddenly drops to unusable speeds often

My house has several wifi networks that are for specific purposes. Basically, there’s one for our slower computers, and the new router has two connections on it. The two routers are connected to each other to use the same ethernet coonnection.

So basically,
Router2 -> Router1 -> Internet

I’ll also label my wifi networks as Connection1, Connection2, and Connection3.
Connection1 is on Router1 at 2.4G
Connection2 is on Router2 at 2.4G
Connection3 is on Router2 at 5.0G
All 3 are secured with WPA2

When I connect to Connection3, my download and upload speed are great! But I have 50% packet loss.
On Connection2, my download and upload speed are ok, but I still get over 50% packet loss.
On Connection1, my download and upload speed are USUALLY decent at best, but there are random times when it drops to near zero even if no one else is awake. Little packet loss.

Like… This shouldn’t happen:

when I’m able to get 40Mbps Down and 15Mbps Up on other days. Nothing on my PC is using the network, and even if it was, 40 is fast enough to handle a download and surf the web at the same time.

I can’t move my router since I have no way to run ethernet far enough. I can’t move my PC since the room the routers are in already have PCs in there that no one uses.

I tried reconfiguring my wifi adapter since I feel that might be the issue but it doesn’t seem to be the problem.
The problems with Connection2 and Connection3 started within the last 2 weeks. Its to the point that GMod reports pings in the 1700ms range while on most servers (Connection1 acting up is why I got another router in the first place. C1 isn’t mine so I got my own). Connection1 tends to tell me my ping is closer to 200ms to Californian servers (I’m in Atlantic Canada).

YouTube videos are loading in 144p and still buffering. I’d like to actually be able to do stuff on my pc. Any ideas?

Seeing as you got multiple wireless networks, are you sure they use a different radio frequency from each other? Perhaps there is a conflict going on with them. What happens if you kill connection 1 & 2 and try using connection 3 as an example?

If that is not the issue, and if there is no way of getting an ethernet cable hooked to your PC from the router(s), perhaps you need a Wi-Fi range extender. That should improve the connection, but as a side effect it will probably cause an even higher latency to your router.

Before doing that though, what I would try to do personally is to use my phone and walk around the building to do some bandwidth bench-marking just to see if there’s something interfering with the Wi-Fi connection. Try walking different distances and go to different rooms, see if there is any big difference in speed/packet loss.