I have an Epson Stylus Pro 9900 printer that is directly connected via ethernet. When connecting the printer directly to the second ethernet port on the PC via a crossover cable, it works fine. When connecting the printer to the router (tried cat6 and crossover), it's not seen on the network.

The PC's internal IP is 192.168.0.xx (router). The printer's is 192.168.100.xx (direct crossover).

First question, why is the printer on a different network than the PC when connected directly? Is that because of the direct-connection? The crossover cable? Both? I assume bypassing the router is part of the reason, but unsure about the implications of the crossover cable.

Second question, any ideas why the PC can't see the printer on the network when it's plugged into the router? Again, tried cat6 and crossover from printer to the router. Maybe this printer model is only able to function via direct connection?

Looking at the printer's front panel, there are no options to set (or even view) it's IP address.

  • You have two subnets running. Why? Did you connect a router to the modem and then use ports on both? For many years router and modem ports have been autosensing and so cross over cables tend to get in the way in normal use.
    – John
    Oct 17, 2020 at 15:37
  • This is my step-dad's setup. The printer is very old and so is the PC (running WinXP!). The PC and printer have been through many moves and connection configurations, but apparently Epson tech support told him he must use a crossover cable to be able to connect via ethernet. I should note I tried connecting the printer to two different PCs on the network via the router: a Win10 PC and the old WinXP PC. Neither worked. EDIT: Shouldn't the printer use the same subnet as the PC when plugged into the router?
    – Jeff
    Oct 17, 2020 at 15:41
  • "Shouldn't the printer use the same subnet as the PC when plugged into the router?" Yes it should but really old printers and XP cannot deal with modern gear because SMBv1 has gone.
    – John
    Oct 17, 2020 at 15:46
  • "really old printers and XP cannot..." Understood. If I understand you correctly, this must be a limitation on the printer's side because even the Win10 machine wouldn't see it.
    – Jeff
    Oct 17, 2020 at 15:48
  • 1
    I will definitely let you know. We also have a 7900 which also connected directly to the Win10 box via crossover with an off-subnet IP. Lots o' money.
    – Jeff
    Oct 17, 2020 at 18:56

1 Answer 1


First, for instructions on setting the IP address of the printer from the front panel, reference the Network Guide for this printer (I found it here:[https://files.support.epson.com/pdf/pro79_/pro79_ng.pdf] 1) on page 39. I strongly recommend trying DHCP configuration first.

The crossover cable (vs. straight-through / patch cable) should not impact the IP addresses usable by the printer. It may impact whether the two devices are able to communicate at all, however.

When you connect the printer directly to your computer, you may have configured the second ethernet port ("interface") on the computer (that the printer was plugged into) to have an IP address and network setting that permits communication. Alternatively, if you did literally no configuration, it may be that both (computer and printer) interfaces would auto-configure, and it does appear that the printer can afford some function in such a state.

  • Great answer, thanks. "It may impact whether the two devices are able to communicate at all, however." This is the crux of my question. Why would Epson tech support tell me that it must be connected via crossover cable? Is this printer even capable of being plugged into a router and detected or must it be directly connected? I only ask because it's so old and am clueless.
    – Jeff
    Oct 17, 2020 at 15:53
  • Because the network expansion ports do not support mdix. It was the same way with the 9800 & 7800. These things are glorified x-y plotting machines. It's not all that old for these guy, our 9800 has over a million feet printed on it! They last for a long time if you take care of them. Oct 17, 2020 at 17:22
  • Thanks @Tim_Stewart, can you tell me if this thing will work plugged into a router? Or must it be direct-connect?
    – Jeff
    Oct 17, 2020 at 18:03
  • I've been told that the next ones up are better with their peripherals. Do you get a link light on the router when you plug in the cross-over cable? Oct 17, 2020 at 18:06
  • 2
    The printer is designed to connect to a router with "normal" (straight-through / patch) ethernet cable. So is your computer. When you connect two devices designed to connect directly to network equipment instead, you need to use a crossover cable. Essentially, the ethernet port in the router / switch is wired differently than your computers ethernet port. Modern computers / network cards support MDI-X (which @Tim_Stewart mentioned) which permits patch cables and crossover cables to work interchangeably. Oct 17, 2020 at 19:37

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