So I had 3 separate Pi3 computers on a LAN made of Cat5 Ethernet cables and a home router. One was a WWW server, another an API server, third one a DB server.
I upgraded them to Pi4 and now I observe great packet loss, extending up to 40% of pings. All three exhibit this effect. SSH barely works but running "apt-get update" usually times out after some megabytes. Effect also occurs on LAN only and besides, my internet connectivity is fine (I'm posting this over the same connection).
- power supply cables (they are powered via thin cables from a common 5V 8A supply to their GPIO power pins)
- gigabit ethernet issues (maybe they're trying to operate on gigabit speeds, but my router or cables don't support that)
- IPv6 seems unrelated, I tried disabling it an nothing changed
Has anyone encountered similar issues, or can anyone please tell how to force a Pi4 ethernet adapter to 100 Mbit speed?