Can't connect server to router via ethernet; router is not projecting signal.
 

I'm using an old Dell XPS Desktop as a fileserver with Linux Mint. I was using dhcp and doing ftp transfers with filezilla. I've since started using gftp. At one point the host ip changed and I could connect, but couldn't do transfers, so I edited /etc/network/interfaces with a static ip, which I have since changed back. (It was around this time when the router stopped projecting a signal.) It reads:

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp

auto wlan0
iface wlan0 inet dhcp

Since then, I bought a new used router hoping to alleviate the problem, which is also not projecting a wireless signal, and which I cannot connect to via eth0 from wither computer. The ethernet cable is connected from the computer to the router, which is connected through one of the ethernet ports, NOT the internet port. The router is plugged in. The router's wireless blinky thing is blinking on and off and I don't know if it's supposed to blink or stay lit. The router is a Buffalo WHR-HP-G300N. I don't know the router's ip address, although in the documentation it says the default ip is 192.168.11.1.

~ $ ifconfig eth0
eth0 Link encap:Ethernet HWaddr 00:13:72:24:c2:88
inet6 addr: fe80::213:72ff:fe24:c288/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:4037 errors:0 dropped:0 overruns:0 frame:0
TX packets:29792 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1365763 (1.3 MB) TX bytes:8346419 (8.3 MB)
Interrupt:17 Memory:fbee0000-fbf00000

~ $ ping -c 3 192.168.11.1
connect: Network is unreachable

I don't think that HWaddr is the right one. I think that is the HWaddr for the previous router. I'm also not sure how I would change this. Help?

I don't know what distro you're using. Many distros have a command 'ifup' (and complementary 'ifdown') to start an ethernet interface. Newer ones use NetworkManager, which obfuscates things in cases like this. At any rate, try
Look for any telltale results that may identify whether a DHCP server has responded, and potentially it's IP. You may have to find the full location of ifup. Ifconfig suggests that your ethernet interface is working, since it is reporting non-zero traffic for both incoming and outgoing data.
--- rod.

On your "Buffalo WHR-HP-G300N" do a factory reset, the factory rest button is on the back of the router, you might need a pen or pencil to push the button all the way in and hold for 15 seconds or until ALL of the lights flash, this should now get you connected to the internet but just try one computer at a time to see.

As aforementioned I'm using Linux Mint on the server because my roommates have also been using it for playing pingus and such. I reset the new router and it's working! Sort of. eth0 is working, router projects a signal, I can connect to the network from another computer, and I can even do file transfers, downloading from the server remotely. Only thing is I can't upload files from a remote computer to the server due to "insufficient permissions." Does this sound like anything familiar? Are there some command line diagnostics I should run to clarify what the issue is?

Your "insufficient permissions" could be due to the firewall...
 

Have you got "Samba" running?
If not download it for both computers.
Have a look inside your firewall and make sure that Samba is listed/ticked on there.
When you have set up Samba you will need to connect your computer(s) to the server.
Hope you know your password(s) and username(s) for both boxes because you will need them for access to either boxes.

I don't have a firewall on either computer. Is there any reason I should switch to samba rather than just using filezilla/gftp? I dont have any windows systems on the network, although my neighbors might, many of whom have our host/user/passwd information. I guess I would just rather figure this out using the programs I've been using if it's possible.