Three weeks later, the background check system is back up and running again. Three weeks of gun sales are going to take a while to process. Nevada needs to be on NICS. DPS has not inspired confidence at all in their ability to run background checks or catch everything they are supposed/touted to. 

Look at this high-profile failure in the case of the Nevadan who drove to New York to shoot up a Manhattan office. 
LVRJ: NYC gunman’s background check not completed, red flag law not used

As the third week of an outage due to a cyberattack begins, Nevada FFLs are still unable to run background checks as the Point of Contact section of the Dept. of Public Safety is "down." If you don't have a CCW, it's impossible to buy a gun in Nevada right now. Dealers are reporting that they have stacks of purchased guns and background check forms just waiting for DPS to get it together.

Remember, the 3-day window starts when the background check is received by the state, not when you fill out the Form 4473. Holders of CCWs get an exemption and a background check is not run.

Nevada runs its own background checks, including for private sales (which must be done through a dealer). 
One alternative is to see if NICS, which is done by the FBI can temporarily step into the breach, which the governor is being urged to do. The problem is that NICS won't do it for a state if they have their own program, as we found out when 2017's Question 1 tried to ban private checks with a dual NICS/state system.

As people will remember, during the panic of 2020 DPS was so overrun with background checks that it took days to weeks for them to be processed. Dealers were on the phone all day just trying to get through. Faxes were the only viable way to get anything done and then not in a timely manner. Nevada's background check system and DPS is a miserable failure that has repeatedly denied citizen's their Second Amendment rights.

Though it will not fix anything in the short term, the responsible people for IT should be fired by the state for allowing the cyberattack to happen and be so disruptive. Heads need to roll at DPS for their inefficiencies and failures for the background check system.