Both firmwares are Connectkey, 071 is Connectkey 1.0 and 072 means Connectkey 1.5
we can't troubleshoot "don't work anymore".
Yes it can be downgraded, but only by an ALTBoot, meaning you need a tech to do it and it will wipe the device entirely, you cannot use a clone to restore it.
You would be vastly better off troubleshooting the issue, which is likely in the scan settings themselves, or the time on the device is wrong, but "don't work" is far from enough to work on, you need to provide at the very least:
1. OS of scan location
2. Failure at the device (Login or connection failure at least)
3. One touch, Workflow scan template, or Scan to is used
4. Domain or local credentials used to access server
5. LAN details about bridges, wired,wireless, corporate or residential