ES-48-Lite to ER-8-XG over two UF-RJ45-10G modules and Cat6: DHCP takes a minute and traffic will not pass

An out-of-the-box ES-48-Lite (1.9.3) was connected to an EdgeRouter Infinity ER-8-XG (2.0.9-hotfix.2) with a UF-RJ45-10G module on each side and a Cat6 cable. A laptop on the switch obtained a DHCP lease from the router only after about a minute and then could not reach the router or the internet, while switch-to-switch traffic worked; discovery saw the routre. The poster had tried trunk settings, enabling IP routing on the switch, an IP on port 0/49 and a default route.

• Hardware: Ubiquiti EdgeSwitch ES-48-Lite, Ubiquiti EdgeRouter ER-8-XG
• Transceivers: Ubiquiti UF-RJ45-10G
• Form factor: SFP+

Symptoms / messages:

DHCP lease takes about a minute
no traffic through SFP+ uplink