24-port switch breaking everything else on the network
I ordered two TP-Link 24-port unmanaged switches from Amazon recently to replace a pair of very old Netgear switches on the church network. I bought these in particular for the "plug-and-play" promise. Turns out it's more "plug-and-pray..."
After plugging the uplink into port 1 on the switch, and connecting all other cables to the switch, I plugged in the power cord. Lights flashed. Everything looked great. And then behold, it came to pass that every single other device on the church network -- across four buildings -- could not access the internet.
Unplugged the new TP-Link switch; immediately everything else not needing to route through that switch was back online.
I downloaded the TP-Link Configuration Utility, plugged the switch back in, and refreshed the utility. It (understandably) said "Unable to find any switches on 192.168.1.x." So I took the switch into my office, unplugged my Windows 10 PC from the switch where it goes, and connected it to the TP-Link switch on port 1. I then restarted the PC and ran the utility. Now the utility reports "unable to find any switches on 239.178.54.14." I have no idea where that IP came from, so it must be the switch?
In any case, I'm completely frustrated by this experience. What does it take to make this router go? Please help -- Sunday is coming, and I've already said the Lord's name too many times over this experience today....