I have 2 TL-SG108PE 8-port switches in my environment. I have PC's plugged into Polycom phones plugged in on the same switchport.  The switchport is configured with the data(PC) on VLAN 3 untagged and switchport PVID is 3, and the Phone is VLAN 4 Tagged.  The data and Phone both work but I am getting users saying that say they get intermittent drops in either Internet connectivity(on the PC) or the phones say the line is unregistered.  Connectivity usually returns after a few seconds.  This is only happening to users that connect to these switches. Is there something I am missing in the configuration, like QoS or something else.