Optical Slots Contamination and Damages
The optical link is not working properly due to contamination and damage to the optical interface. The end face of the fiber connector and optical slots is exposed to the environment and contaminated by dust. Using the scratched or poor-quality fiber connector will cause the SFPs failures.
ESD is the abbreviation of electrostatic discharge. ESD will absorb dust, change the impedance between lines, and affect the function and life of the product.
Most of the manufacturers guarantee 100% compatibility, which might not be the scenario. Once you find the modules are not compatible, you’ll have to troubleshoot them but with no visible outcomes.