It is a compatibility issue between 3G expander and 6G drives. 3G expanders may be not able to get 3G link speed with some 6G drives when the expander configured with auto link speed detection mode. Force drives or expander with 3G mode will be necessary to avoid this link speed issue. You can login the expander manager through the RJ11 on bracket to configure expander with 3G mode, or you can configure the hard drives link speed instead.
Tags: ARC-1680ix-24, drive