file system check exit code is 6

On my 2011 mac mini running "High Sierra" I noticed a 14TB external Hard drive was reeeeeeeeeeealllllly slow so i ran the disc utilities "First Aid" function and it fails every time. I get a "file system check exit code is 6" But when I search on google i can only find "code 8" issues . Anyone know what code 6 is? I am not looking forward to dumping over 10gb of Data onto other Hard drives until Im sure I have to, expecially because its 5 times slower than usual. I tried to transfer 75gb worth of data and it took about 24 hours. eeeeew. The drive still works its just very slow. I haven't unplugged it yet but just wanted to see if anyone knew before I disconnect it and started copying the data over somewhere else. Other HDD work like normal.