Link Down when power is available

Hello, I'm not familiar to Mikrotik switches but to troubleshooting you can try some below steps:

• Check the physical connection and make sure the QSFP+ cable or module is properly inserted and secured on both ends. You can also try swapping the cable or module with a known working one, or use a different port if available.
• Check the port status and settings on both devices, such as speed, duplex, mode, VLAN, and LACP. Make sure they are consistent and compatible with each other. You can use the show interface command on the Dell switch¹ and the interface print command on the Mikrotik switch to view the port information.
• Check the software version and firmware update on both devices, and see if there are any known issues or fixes related to the QSFP+ port or interconnection. You can use the show version command on the Dell switch and the system package print command on the Mikrotik switch to view the software information. You can also visit the official websites of both vendors to download the latest software or firmware updates.
• Disconnect both power cables from the main optical switch, Dell Force10 S4810². Once powered off, disconnect the power cable from the switch below, Dell S3048-ON². Once both devices are fully powered-off and after ~10 seconds, reconnected the power to the Dell Force10 S4810 optical switch and allow the device some time to fully initialize