Why does my Linux PC disrupt the entire network when it goes to sleep?

The adapter and its power-management behavior are worth investigating, especially if it is connected through a USB dock or USB Ethernet adapter. Some adapters can generate malformed traffic or pause-frame floods while entering a low-power state. Run `lspci` and `lsusb` to identify the hardware, and test with another adapter, another cable, or Wi-Fi if possible. You can also check the sleep mode with `cat /sys/power/mem_sleep` and inspect wake sources using `cat /proc/acpi/wakeup`.

Check whether the Mint installation is providing any network services such as DHCP, DNS, routing, or a proxy. If another device is accidentally relying on this computer for one of those services, putting it to sleep could cause widespread failures. However, if no such services are running, this sounds more like a network adapter or router interaction.

Wake-on-LAN would be one of the first things to test. Disconnect the Ethernet cable while the computer is asleep and see whether the rest of the network immediately recovers. You can usually disable Wake-on-LAN in the BIOS or with NetworkManager. From Linux, check the current setting with `ethtool | grep Wake-on`, then disable it temporarily with `sudo ethtool -s wol d`.

The best way to find the cause is to capture traffic while the machine is asleep. A multicast storm, excessive broadcasts, or another faulty Ethernet behavior could overwhelm the router or switch. `tcpdump` or Wireshark should show whether the sleeping computer is still transmitting unusual traffic. Also check the router's logs and whether the problem disappears when the cable is unplugged.