Re: ip-source-guard/dhcp security blocking lease renewals

On the EX4300 when you enable any Security feature, like IP-Source Guard, the switch automatically enabled Dynamic Arp Inspection (DAI), which is a requirment for IP-SG to work.  Go to:

https://www.juniper.net/documentation/en_US/junos/topics/concept/port-security-ip-source-guard.html

See the 1st Note under "How IP Source Guard Works".  There is also a link to CLI procedure to configure via ELS.

You may want to look at DAI nfo here and use this to check what is going on there:

https://www.juniper.net/documentation/en_US/junos/topics/example/port-security-protect-from-spoofing-els.html

Good luck.