Strange Network Switch Fault [closed]

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http://serverfault.com – My office recently opened a new branch, to which network connectivity was provided via fiber optic line and a cisco switch. From there onwards vis UTP cable and unmanageable (and admittedly not-so-high-quality) switches. Everything worked fine for a few days, but recently, during certain time of the day (usually early afternoon and late evening) the connectivity to certain sections drop. Eventhough the port lights are green. A restart of the faulty switches sometimes fixes the problem, but only temporarily. It cant be due to the cisco switch, as my own departments unmanageable switch works f (HowTos)