Hello,
Could you check, if the both RUT devices are in different subnets?
Are you able to access RUT1 if you connect your PC/Laptop to the LAN port of the PoE injector? This would ensure that DHCP from RUT1 is working.
Otherwise, could you replicate your setup and configuration, login to RUT2's WebUI, go to System -> Administration -> Troubleshoot section and download troubleshoot file from there. Attach the file by editing your question. The logs in the file might provide more insight into the issue.
Best regards,