This week, one of my printers stopped working. The symptoms were that I could print from my program (whatever type: browser, Word, etc.) but couldn’t actually get anything to show up on the printer.
Windows 7 showed me a printer icon in the icons displayed at the bottom right-hand part of the task bar — the section that shows notification icons. When I hovered over the icon, it told me that there was one documented pending for me. No hint as to why, though.
When I opened the Start Button and selected Devices and Printers, the Printers and Faxes section looked like this:
The yellow warning triangle at the corner of my color laser printer told me there was a problem, but again, nothing hinted at what it was. If I hovered over the icon, I got a popup that said "Status: Printer: Error" and "Status: 2 document(s) in queue."
The key to this problem is that this HP Color Laserjet 1518ni printer can be connected directly to a computer, as most people do, but it also has a network interface ("ni") and can be connected directly to your network hub or switch (including the switch that’s built into most routers).
It took some thinking, but the problem happened like this…
First, the printer was set to automatically get an IP address on the home network. This was the default setting.
Then, when I had Windows find the printer, it did that — but it specifically set the printer to connect as a specific IP address 10.47.15.106. All well and good so far. Windows also gave this "port" a name that matched — 10.47.15.106.
Now, we have to consider what happens when you use DHCP to get IP addresses automatically rather than specifically setting them yourself. The IP addresses are "leased" by the DHCP server (which in most cases is in the Cable/DSL router.
When the lease expires (which might be a day or a month), the device that requested and received the address will automatically ask for the same address to be renewed. If the address is available, fine. If another device has grabbed that address (perhaps the previous device was turned off while the lease had expired), a new IP address will be assigned. Or, if the router get’s its power turned off, it will lose the memory of all the current leases.
That’s what had happened here. Because of some Internet connection problems, we had forced a manual reboot of the router by unplugging its power cord for a few seconds and then reconnecting it. Everything worked fine, except the printer — or more specifically the Windows 7 configuration of the networking for the printer — which remembered its old IP address and didn’t change its setting.
I checked the printer itself to see what IP address was set and found that it was now 10.47.15.112.
Now it was just a matter of changing the "Printer Name or IP Address:" in Windows (on the Port Settings) tab and clicking OK. Note that the Port Name can be changed, which isn’t necessary, but it is not done via this particular dialog box.
Once I changed the dialog box to use the IP address the printer received, all was well.
As a more permanent fix, I changed the printer to get its IP address by manual setting, instead of automatic. I gave it an address outside the range being allocated by the router, so that the problem doesn’t happen again.