I've been running a Minecraft server with some friends and it seems to have a strange problem. The server, right now, is running on my laptop at home, connected via wireless. At home I have two desktops, one is wired and one's wireless. Almost every time that I try connecting to the server from the desktops, it fails. When I try pinging the laptop, it fails ("Destination host unreachable"). To temporarily fix it, I can ping the problem desktop from the laptop and it instantly starts working fine. Once connected, it stays connected without any problems. People connecting from outside the LAN don't seem to have a problem, but I haven't really tested that very much. Any theories?
Make sure firewalls are turned off on the computers (Windows Firewall) Make sure any router settings for firewall such as block ping requests are turned off Make sure your laptop has a static IP set make sure your desktop is set to a static IP Router firewall is still ok to have on Example: router's IP = 192.168.1.1 desktop settings: IP - 192.168.1.111 subnet -255.255.255.0 gateway - 192.168.1.1 DNS - 192.168.1.1 laptop settings: IP - 192.168.1.112 subnet - 255.255.255.0 gateway - 192.168.1.1 DNS - 192.168.1.1
Are the wireless and the wired PCs connecting to the same wireless router/switch? This sounds more like a missing ARP entry than anything but that isn't a common problem. We can test this by looking at your ARP table before and after you do your ping fix. While you can't connect do the following on the PC that can't connect to the server: Open command prompt and type "arp -a" to list all the entries. Code: C:\Users\David>arp -a Interface: 192.168.1.101 --- 0xa Internet Address Physical Address Type 192.168.1.1 00-23-69-0d-e0-d1 dynamic 192.168.1.255 ff-ff-ff-ff-ff-ff static 224.0.0.2 01-00-5e-00-00-02 static 224.0.0.22 01-00-5e-00-00-16 static 224.0.0.252 01-00-5e-00-00-fc static 239.255.255.250 01-00-5e-7f-ff-fa static 255.255.255.255 ff-ff-ff-ff-ff-ff static In my case here I only have one dynamic entry and that is for my default gateway to the interwebs. In your case you should have your default gateway and a second dynamic entry for your server's IP and MAC. If not used the entry is dropped from the table after a timeout period(default 5 minutes or 300 seconds.). Now do your workaround ping and check this table again and I bet it shows up. The question is why is this failing. I could be a firewall setting on the server not letting ARP requests complete. 2 fixes... fix the firewall or make a static MAC entry on the PC trying to connect. I don't know your firewall so I'll give you #2 although this is not the best solution. Make sure the server has a static internal IP first. Then find out the MAC address of the server by doing your ping from the server then check the ARP table again. Once you have this add a static entry with this command/ "arp -s <IP> <MAC>". Like this: arp -s 192.168.1.101 00-50-04-62-F7-23
I set the server laptop to a static IP (mistakenly thought it already was) and it seems to be doing fine. I suppose I'll come back if the problem happens again.
Ok, so it's still happening, though it seems to be less often. It seems like I'm having a problem setting static IPs. To check if I was doing it right, I did pretty much exactly what's stated at http://portforward.com/networking/static-win7.htm Right now the server laptop is using: Code: IP: 192.168.0.11 Subnet Mask 255.255.255.0 Default Gateway 192.168.0.1 Preferred DNS server 64.71.255.198 Alternate DNS server 192.168.230.2 I called my ISP to get the DNS addresses. I've tried doing this for both the desktop PC and the server laptop. When I do the arp -a on the desktop, it gives me the following: Code: Interface: 192.168.0.5 --- 0xa Internet Address Physical Address 192.168.0.1 00-26-f3-96-bd-d7 dynamic 192.168.0.255 ff-ff-ff-ff-ff-ff static 224.0.0.22 01-00-5e-00-00-16 static 224.0.0.251 01-00-5e-00-00-fb static 224.0.0.252 01-00-5e-00-00-fc static 224.0.0.253 01-00-5e-00-00-fd static 239.255.255.250 01-00-5e-7f-ff-fa static 255.255.255.255 ff-ff-ff-ff-ff-ff static After pinging the desktop from the server laptop it adds this line: Code: 192.168.0.11 90-00-4e-16-ed-d6 dynamic I haven't tried adding the arp entry because it's still showing as dynamic. I didn't skip any steps with setting the static IP, so I'm not sure why it's still showing as dynamic. If it matters, I'm using an SMC3DGN modem/router. Firewalls are off on all computers and the modem/router. Should I do the arp entry with it showing as dynamic or is there something else I should do?
I doubt this will help you at all, but I think it is more "proper" to set the DNS settings in your router, and then for the DNS of each computer it should be the routers IP address, that way each computer pulls the DNS settings from the router when doing things. That way you dont have to set all the DNS addresses on all the computers and if you ever need to update a DNS then it is easier because you only update in 1 place, the router. At most you could use the secondary DNS as a backup for pointing to a real DNS server in case the router ever fails to provide the needed info. At least thats how I learned it. Maybe that is wrong and if so Q can correct me on it. As to your problem, that is too technical and obscure for my knowledge and Q will have to help you there. He knows a LOT more about advanced networking than I do. I am more of a hardware person and he is a networking person. But my guess is, if the router's IP is said to be dynamic even though it is a set static address, then it is probably fine that the server (which is also set as a static address) reads as a dynamic entry.
There isn't much concern here. Just be mindful if you change ISPs you may have to change your DNS entries. I assume DNS is working just fine for you at the moment so I would not change it until the you have this current problem handled. We want to keep the variables to a minimum.
Ok if you haven't added the static entry lets try a little experiment to see if we can trigger the problem. Your PC flushes all arp entries after 5 minutes of no communication to that IP. I don't know of any background processes that may be doing this but we can flush the arp cache to force the PC to have to rebuild the dynamic entries. Use the following command to flush the ARP entries of the PC trying to connect to the server: netsh interface ip delete arpcache Now see if the problem returns and I bet it does. Lets then try to add the static entry and see the the problem goes away: arp -s 192.168.0.11 90-00-4e-16-ed-d6 If you ever need to remove this entry the command is 'arp -d 192.168.0.11 90-00-4e-16-ed-d6'.
I tried to add the ARP entry and it states: The ARP entry addition failed: Access is denied. I've tried both before and after pinging and it gives the same error. I double-checked to make sure there aren't any firewalls on for either computer or the router.
Try running command prompt as admin. This is easier than me typing it out: http://www.howtogeek.com/howto/wind...administrator-from-the-windows-vista-run-box/
Been doing some reading and that may not work either in 7 or vista and you must use netsh. source: http://social.technet.microsoft.com.../thread/9382ced0-6575-47d6-89d7-8b1581ff60f1/ open admin command prompt again and try this: netsh -c "interface ipv4" this command is going to enter the the configuration context under interface ipv4, then you will see the prompty become like 'netsh interface ipv4>' type --> set neighbors "Connection_name" <IP> <MAC> After you done this you can check it wil arp -a and you can see that it has be added statically
Many people dont know how to do this. Clicking on run and then typing "cmd" doesnt get you an admin level command prompt. You can tell whether you are in admin or not because the non-admin will says C:\Users\"username" whereas an admin level will say C:\windows\system32\. I find the easiest way to get to an admin level prompt is to browse to C, then click on Windows folder, then the system32 folder, and then open the "cmd" from there. Right click it and "run as administrator"
I've been playing as normal since using the netsh neighbors and it's working fine. Thanks for the help guys!
Glad to hear everything is working for you now. This still doesn't fix the root problem but it is a working bandaid.