I have an SG550XG that has worked for quite a while, but recently have had issues with DHCP relay. I have the default VLAN and 2 other vlans (20 and 100). The default VLAN is on a 192.168.x.x network, VLAN 20 is on a 10.0.x.x network and VLAN100 is on a 10.100.x.x network. I never have issues with the default VLAN and most of the time I don't have issues with the other VLANs. However, randomly, I will have a client on VLANs 20 or 100 that get an IP address from the default VLAN and therefore no traffic will pass. Usually, the fix is to disconnect from VLAN 20 or 100, connect to the default vlan and then back to your VLAN 20 or 100 and it will work. Sometimes it takes two times of going back and forth to make it work. I have also found that if I get an incorrect IP address for the VLAN but then manually put in a correct IP for the VLAN, and then set it back to DHCP, it will get a correct address after that. I am one firmware version behind current, so I plan on updating the firmware over the weekend to see if that fixes it.
Right now, I created one test port as an access port on VLAN 100 and my laptop won't get an IP on the VLAN 100 network unless I manually put in a correct IP for the VLAN and then go back to DHCP. So it has to be my core SG550XG switch. Also, the DHCP server is on the default VLAN and directly connected to the core SG550XG switch.
