I have noticed this too, and will be raising awareness of it, in an attempt to get it resolved. Hopefully it should be back up in the near future.
Hello,   I am have been looking for firmware downloads for the 6224f and 6248 powerconnect switches on the Dell support site.   It looks like this series of switch is no longer listed on the Dell support site.  I was able to find firmware a few months ago.   Can anybody point me in the right direction for the latest firmware.  
Powerconnect 6224f and 6248 firmware downloads no longer listed on Dell support 
site?