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Severe stability issues on my local network

Hello Hivemind 🙃

i need some advice here as i am losing my mind.

I have a Fritz!Box6591 and 1Gbit/s internet. Now since yesterday my complete network is extremely unstable. IF i can get any connection, it's as fast as it should be. But connections break down within minutes.

If i let the network "rest" for a couple minutes with barely no activity, i can then access everything perfectly fine for a few minutes until everything breaks down again.

What i did:

-Deactivated my local DNS (AdGuard) on my router -Restarted (even with 15 min. of no power) EVERYTHING. Literally everything in my homenetwork.

Since it's not only the internet connection and not one specific device and not even one specific type of connection (two WiFi Devices can't properly connect between each other just as two different LAN Devices on either different Ports on the router or same router port on a switch) i don't really know what to do anymore.

Obviously my router is the only common denominator but i can't see any issues with it. It's not overheating, it's RAM & CPU usage is perfectly fine, it's not gone it powersaving mode, it doesn't throw me any errors.

I already did tracepath's to every device and there is no unexpected hop on some theoretical phantom device (if my DNS became buggy or something).

If i ping one of my servers from my PC. It says i have a latency of 1~3ms but it is obviously hanging really hard. It could have a delay of 15 seconds before the next line in ping appears but that will still claim it had a 2ms latency.

I don't know what to do anymore and where to begin. Any ideas?

EDIT: Here is quick sketch of my network

EDIT2: Found the culprit - https://lemmy.dbzer0.com/comment/324192

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  • My guess was gonna be a broadcast storm caused by a loop. Like a device that's connected to 2 different ports. That or a rogue dhcp.
    Either way, taking a capture in Wireshark would have helped.

    If these are managed switches, configuring bpdu guard on LAN ports (not on trunk ports to other switches!) would prevent a device from forming a loop.

    • Never worked with wireshark^^ but i guess i should learn to use it in case something like this happens again....

      No they are unmanaged switches. that's why i don't have VLAN aswell.

      • I find it useful even as a teaching tool.
        Even when your stuff works, visualising packets on the network is something that helps with understanding networks in general.

        Wireshark can be overwhelming when there's a lot of traffic, but if you start with a basic setup and less noise, things make more sense.

        When I coach someone I go through the very basic of getting internet connectivity while having Wireshark open, without your gazillion apps all phoning home.
        Just DHCP, ARP, default gateway, DNS, TCP, HTTP.

        A decent part of becoming an expert in Wireshark is learning how to filter to see the exact traffic you need to see.

        • yeah i just installed it and was already a bit overwhelmed at what to do... this seems like a nice project where i can just play around with until something works out for me.

25 comments