Series 9020 will print only intermittently.

[Angel2063]

Print jobs are delayed and will print hours later or sometimes will not print. The printer is online. I have tried Fix and Diagnose, but it says the problems have been fixed.  The test page will print much later, but other jobs in the que will not print.

[BeemerBiker]

The printer may be going to sleep. When I wakes up it may have a new IP address. When this happens it may take a while before the PC can find the new IP address.

See if helps if you disable sleep on the printer using the EWS page

The printer is waking up from sleep and getting a different IP address than it had and your PC cannot communicate with it anymore. A quick fix is to set the sleep to off or never. Access the printers embedded web page and set sleep to off or never.

If the printer keeps changing it's IP address then a change to the modem is necessary. The printer needs to be assigned a fixed IP address that is reserved and does not change. This is necessary on flex networks (multiple wifi booster / repeaters)

Assigning a fixed or reserved IP address is done in the modem as part of DHCP configuration.

First get a network report from the printer so you know its IP address or Mac address
Log into the modem and look for the DHCP server. Find the IP or Mac address of the printer and make it a fixed IP address.

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Another problem is that it simply could be a bad signal strength that dropped out and then picked up later. The jobs in the queue may not print unless they're restarted.

If the problem is a signal strength to a router and the printers near the PC then you may want to use WiFi direct.

For WiFi-direct read page 40 of 9025 or read 9020 page 145