25G SFP28 DAC

Does what is asked

This DAC cable is causing me problems . I am setting up a 25 Gb Network for my Home Office and have just received my Switch from Qbiquiti and my 25 Gb NIC from Mellanox today 27th July 2023. I bought this cable early in May as a test to try out and set up my Network with 4 other PC to be connected, when i would receive the backbone Network switch.Plugging in the DAC to my switch gives me an inter mitten connection at best and it just not give me a solid connection, getting bad drops off and complete disconnections at random times which can been seen on the switch connection light.When I do get a connection a 60Gb file using my 10 Gb connection I get the full bandwidth at just over 1.1GB file transfer from NVME to NVME drives. When using/testing I am getting mad fluctuations from 300 M/B to about 700 M/B when testing the connection and the same file, takes twice as long to complete in time using the 25GB connectionThis is a sealed DAC so something is wrong with the lead. Transferring from the Work Station to the back up PC gives me the full speed of the 25Gb connection but can drop out, the problem is the testing the file transfer from the back pc to the Work Station where I get these slow connections and drop outs.I have reversed the cable end to each PC and the same thing happens . I have tried everything and so have ordered a 3m cable here from 10Gtek to see if that will solve the problem along with other brand name cables of the same connection SFP28. Just a process of elimination and the fault every time points to this cable.I have bought 10GB cables from 10Gtec on my 10 GB Network and have had no problems. This is the only 25GB cable I have to test with and glad that I did not spend any more on my 2 x 25 GB Mellanox port Nic.Amazon say I cannot return this after the 30 day return window, I am a bit disappointed, but due to server and NIC shortages I am only able to set up and test the new System now after a 1 year waiting time.