Why are packets lost when connecting multiple devices through a LAN router?

Question

network hardware

Good afternoon. The problem is this. Communication works fine without connecting a router (i.e. if the cable is directly plugged into one computer). As soon as I connect the wires to the router, packets begin to be lost. The firmware is the latest. Apparently, this does not depend on the router, since I changed 3 routers, but the problem did not go away. All wires are crimped. Some of the IP addresses are automatic, and some are static (necessary for equipment). But even if one computer is turned on after the router, then the problem with the loss of part of the packets is repeated. Tell me what could be the problem?
upd: the problem was a virus at the checkout. The source was the UKM server in St. Petersburg.

Answer 1

I do not fully understand the connection diagram (a diagram would be helpful), but I suggest checking the settings for auto-detection of the duplex and data transfer rate of the medium. In particular, auto-detection settings from the opposite end of the "cable" that you plug into the router. If the speed and duplex are hard-coded (100/full) on the device/devices from the other end, for example, and are determined automatically on the router, then it is quite possible that the router port will rise in 100/half mode. This is fraught with packet loss. Also check the duplex settings on the links between computers and routers.

Answer 2

here is the diagram