Sorry to hijack your thread, but While yall are discussing switches /networking I have a problem that I could use some help diagnosing. My office network consists of a a new lenovo server running Server 2012 hosting AD-DC / DNS responsibilities (Single DC / single DNS, no secondary for failover...Yes i know) There are approximately 50 client computers with 95 percent being Windows 10 Pro machines/ Windows 7. The network is configured so that it goes

Modem = Router = D-link 24 port Managed switch -DC server - second 2012 server dedicated to running Sql) - 18 client connections - and 2 lines that go to two un-managed 24 port switches on either side of the office complex with approximately 32 Clients split 26/6.

The problem i'm having is every few weeks the 32 computers on the other side the two un-managed switches stop communicating with the DC/ DNS Server causing them to lose authentication/ network shares/ and internet access. Meanwhile the remaining 18 clients and servers connected to the managed switch continue to communicate / authenticate without issue. Eventually after multiple restarts / hard resets the 32 clients slowly begin to reconnect. Server Event viewer shows no DC/DNS warnings or errors, and the client side says cannot locate DNS server. The first time this happened it took 8 hours and the second time 5 hours for the network to stabilize. Ive tried everything i can think of in my limited knowledge of networking and suspect the authentication packets are getting corrupted as they pass through the second network switch (All connections are Gigabit connection and the two un-managed switches are less then two months old. Any input is appreciated.

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Posted by philabuck

NE Ohio

Member since Sep 2008

10380 posts

Posted on 9/15/16 at 8:27 pm to triggs85

What's the brand of the unmanaged switches? I had a similar issue switch a Cisco SG200 being used in a small training room.. Ended up resetting the switch, updating the firmware, and throwing it on a small UPS. Not sure which one of those fixed it, but the problem hasn't come back. I read a lot of forums about a similar issue, but it was mainly people with IP phones that couldn't get them to register. Had to do with the smartport setting I believe.