Hi, It sounds like spanning tree is turned on. Try enabling fastpath Page 267 [URL]
Setup:  I just recently purchased a Powerconnect 5324 and migrated my network over to it.  Steps I have taken so far is updating firmware, setting up the webui, assigning it an ip, failed at setting up SNTP so I disabled it since it was not updating with externap servers.  My router which is a Netgear R7000 is also the dhcp server.   Problem: When a device is connected / power cycles it takes longer than 20 seconds to be able to communicate with the network.  I have tried both static and dhcp ip addresses to see if it made a difference - it does not.  Problem did not exist before converting to this switch and goes away when using old ones so long as its not plugged into this switch but directly in the router.
Slow network identification.