Good way to troubleshoot lan connectivity?



  • The clients on my network are saying they are losing smb connection on their network drive to the server shares. What would be a good way to go about troubleshooting whether its our switch, or our router, or our nic on the server as the cause of the issue? How would I go about ruling out the router in pfsense? What tool would I use to do so?



  • Assuming a typical small network where the clients and server are on the same subnet, you can eliminate the router, because that traffic never touches it so it can't have any impact.

    From there you'll have to troubleshoot further to narrow it down. First step would be to determine whether it's a complete loss of network connectivity (pings drop?), or only loss of SMB shares.



  • @cmb:

    Assuming a typical small network where the clients and server are on the same subnet, you can eliminate the router, because that traffic never touches it so it can't have any impact.

    From there you'll have to troubleshoot further to narrow it down. First step would be to determine whether it's a complete loss of network connectivity (pings drop?), or only loss of SMB shares.

    It is a small network of 5 computers going thru a trendnet switch. The router is in a hyper-v in a new windows 10 box. We are using it for dual purposes at the moment.

    I've checked the event logs for the server under system logs and filtered "tcpip" and nothing at all came up in the logs.

    So basically it's either the server or the switch then. Being event logs are showing up nothing, it must be the switch then.



  • If you can reliably get it to drop connection, you can use wireshark to sniff the packets on both sides and figure out where packets are getting lost or what signals are causing it to break.



  • @Harvy66:

    If you can reliably get it to drop connection, you can use wireshark to sniff the packets on both sides and figure out where packets are getting lost or what signals are causing it to break.

    That's the thing. I'm 3rd party it for them and it's so unpredictable. I'd have to spend all day there waiting for it to happen



  • A switch costs peanuts.  Just replace it to rule it out if there are no other clues.  You can always switch back if it wasn't the problem.



  • @KOM:

    A switch costs peanuts.  Just replace it to rule it out if there are no other clues.  You can always switch back if it wasn't the problem.

    Ive had intermittent issues with a Trendnet switch before myself..  Of coarse that was after a close by lightning hit but non the less..



  • If you were a pfSense Gold subscriber, you would have access to the latest Hangout video "Connectivity Troubleshooting", which would probably come in handy for you right about now.



  • My issue in this area was DNS related.



  • I'd start as most do on the network. Physical layer. (unless you know there was some recent changes made to the network or PFSense).

    Check all hardware including the switch, pcs, cabling etc… for any issues.

    I'd start by checking the modem. If you have a static IP on it you can configure a NIC on a laptop to the static IP and connect it to the LAN of the modem. Remove all other connections and test the modem speeds on a laptop. If all is well reconnect it back to normal and move onto the next step.

    Bypass the switch and next test the PFSense box, plug the LAN from the PFSense into your laptop. Check the connection at this point. Is it slow or stable at correct speeds? If not the obviously the problem is with the PFSense box and not the remaining items on the LAN.

    If it is, then do the same troubleshooting method for the switch. Swap it out with spare for a test. Reboot the switch, do speeds return to normal then die out over time? etc....

    Pinepoint the item causing the issues first. Then you can troubleshoot the cause.

    Just a side note about running PFSense in a Hyper-V.

    I just installed PFSense for my home network and reviewed online documentation that stated to use legacy network adaptors in the VM. When I did that I noticed I was getting very poor download speeds and other packet loss issues. I changed it back to the default adaptors and had no issues since. A lot of the online documentation and videos for setting up in Hyper-V are out-dated and incorrect for today's technologies and recent PFSense releases.


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