I have a support case open, but the engineer want to try reproducing the issue in their lab which could be a few days. So I thought I'd, ask the community as well.
The switches in question are EX4300s running the current JTAC recommended software(14.1X53-D45). They were installed over the weekend, and replaced EX4200s which did not have any issue.
I am having problems with DHCP in a primarily wireless environment. DHCP is set up on a server and a DHCP relay pointing to that server is configured for several subnets. The initial DHCP request sequence of Discover, Offer, Request, ACK succeeds in all cases, as well, the periodic DHCP Request packets when a client requests an IP renew (or when doing ipconfig /renew) succeed. These renews are unicast to the server.
The issue is when a client roams to an access point on a new subnet. After wireless association, the client sends a DHCP Renew (broadcast this time), which the server does not see. The client repeats the DHCP Renew until it times out. Eventually, the client starts the DHCP process over again starting with a Discover, and gets an IP. This whole process is 1-3 minutes. On occasion (5% or less), it will work correctly and the server will recieve the Renew request broadcast from the relay, reply with a NAK, and the client will send the DHCP Discover immediatley and get an IP.
I have checked with another compuer running Wireshark and associated to the same access point, that the DHCP Renew broadcast is being forwarded by the AP, just not seen by the server.
I can't see anything wrong with the dhcp-relay portion of your config.
You might also try some of these options:
set forwarding-options dhcp-relay forward-snooped-clients all-interfaces
set forwarding-options dhcp-relay route-suppression destination
set forwarding-options dhcp-relay overrides allow-snooped-clients
set forwarding-options dhcp-relay overrides always-write-giaddr