 Do cat6 cables work with cat5? All data cable categories from cat5e through to cat8 all have an element of a connector called an rj45. This is for both the module or jack, the female end, and the plug, the male end. Therefore each category is backwards compatible with the others. i.e a cat6 cable will plug into a cat5e module. In addition, cat6 cable can be terminated onto cat5e ends. However, in any data cabling installation, the overall link is only as good as its weakest part. Hence cat5 and cat6 are compatible but it's not the desired solution. Therefore if using different categories the link will only work as good as the lowest grade element. This is sometimes seen however when companies are moving and want to retain parts of their existing infrastructure and instead plan to upgrade at a later stage due to budgets.