The router is claiming ownership of all ip addresses in that range to use as it needs.
You need to exclude some addresses so that you can manually fix them.
The router will not be able to reallocate them dynamically.
If you do not do this you run the risk of conflicts.
Gotcha.That's exactly right. By changing the start (bottom) address to 21 instead of 2, it means we can use the addresses 2 through 20 for fixed IP addresses. So you have plenty of address space for them now. You can still have a huge number of other devices, which can be automtically assigned addresses from 21 all the way up to 253.
If you didn't make this change to the DHCP range in the router, everything might work for a time, but sooner or later the router would assign the address 11, which your printer now has, to another device as well, perhaps a visiting smartphone for example, with disastrous results.
1) It is from mine, but hers now looks the same.1. Which machine is that screenshot from - hers or yours?
2. Did you configure both computers to have the printer on the IP address?
3. Are you now printing OK from both computers?
It sounds as if her computer is trying to write to that IP address, since the printer responds. But the computer may be set up for the wrong printer type, or with a printer setting that causes a problem, such as defaulting to the wrong paper size. Carefully compare all the printer settings on your computer with all the printer settings on hers.If we go through the checklist both PCs are set to fixed IP adresses?