DNS fail, no DNS showing from DHCP?
I've started having some very strange networking problems with my printer since I upgraded my MK4 to an MK4S.
The most recent is a DNS problem. My printer is connected via ethernet, and the network settings for it shows "-" for DNS server. The "Ping | Loss" section says "DNS FAIL" for "Connect". I just started a print via PrusaLink and was trying to check the camera via PrusaConnect when I noticed this, so I can't reboot it until the print is done. This happened before and turning off power to the whole printer fixed it. The reset button did not.
The DHCP server gives out two IPs for DNS servers on the LAN. I didn't have problems with it before, but is that maybe triggering a bug in the firmware? I can't really do much about that, since it would affect everything on the LAN. Does the "-" for the DNS server just mean it can't show two, or does it mean it thinks it doesn't have a DNS server?
Are there any logs I can somehow look at to try to debug what's going on? Is this a known problem of any sort? I am admitedly a bit behind on the firmware, on 6.1.4+7908. It's not the first weird networking problem I've had since I upgraded to an MK4S, sadly.
RE: DNS fail, no DNS showing from DHCP?
Yeah.. hard to troubleshoot.. but maybe there is a physical problem.. Doesn't look like it is hitting your DHCP server on your network.. so I'm thinking a network cable issue. Do you get a green "link" light on your printer where your cable plugs in? Try plugging into a different port on your router. Now is your router's DHCP working.. sometimes they crap out.. but your computer keeps working because it has all the IP info it needs.. So do a power recycle on your router.. and any switches between your printer and the router.. Then power cycle your printer AFTER power cycling the routers/switches. Make sure your RJ45 cable is good.
RE: DNS fail, no DNS showing from DHCP?
It's definitely not a physical problem. It has an IP via DHCP, I can ping the printer over the network, printing to it with PrusaLink from PrusaSlicer works... the printer itself just can't see to figure out DNS, so it can't make outgoing connections.
I powered it completely off and back on and it's working again, just like last time. But this is the second time now that this has happened.
RE: DNS fail, no DNS showing from DHCP?
Oh, I was wrong, rebooting it didn't fix it. It's still showing an IP (from DHCP) and gateway and all that, just no DNS server.
RE: DNS fail, no DNS showing from DHCP?
I updated the firmware to 6.2.2 yesterday. Today while I was out, I got a Prusa app alert about a printer error. I got home to a printer beeping and some kind of network task error. I don’t know why this printer is so unhappy about the network in general!
RE: DNS fail, no DNS showing from DHCP?
Looks like some incompatibility between the printer and the DHCP server in your router.. hard to know what is going on without using a packet inspector to look at the DHCP info being exchanged.. did you ever try a static IP setting to set all the IP parameters?
RE:
Sorry.. I profess I didn't read your original post carefully enough.. at first I thought you weren't getting any IP info. I would guess that the dash just means 2 DNS entries are present and it can't display both.. but that would be bad software design to not display one. You might want to contact Prusa to see what that dash implies.. maybe also search the GitHub firmware site to see if there are any issues reported when using 2 x DNS entries... but I would think that is pretty common. Most DHCP uses the local router as the primary DNS but use the Service Provider as the second DNS entry. If you have easy access to change your DHCP setting, you could temporarily just use one DNS entry to see how it works with your printer. That should not affect your other devices.. DNS servers are pretty reliable.
I do read some DHCP issues with firmware on GitHub but not sure if they are similar to what you are experiencing.. A static IP setting for printer might help. I am not a fan of writing your own TCP stack, as Prusa does, using open libraries, rather than have it hardened and running under a more reliable OS (such as Linus, which is what Octoprint does), but the cost is slightly higher in requiring a decent Pi or something similar.
RE: DNS fail, no DNS showing from DHCP?
If you use static IP, just put one DNS entry
RE: DNS fail, no DNS showing from DHCP?
Just completed my kit and had the same problem with the LAN connection. If I try to connect with a wired connection the printer doesn't get or understand the IP address it gets from the DHCP server. It does see the server, the physical connection light lights up. When I turn the printer on the light flashes implying there is traffic then goes quiet. I can't ping the box. It's not critical for me (I just have a lot of WiFi traffic so I try to reserve it for portable devices. The WiFi seems to work flawlessly. I tried a fixed IP address but it isn't clear how I enter it into the printer. Again, not high priority for me.
RE: DNS fail, no DNS showing from DHCP?
This just became real for me as our schools printers had to be taken off the wifi network and put on wired connections for reasons of school policy. The MK4S printers at the school made the switch from wireless to wired transparently and link to the slicer workstations I setup without a hitch. This made me go back and look at the one I got for my shop. I discovered and intermittent problem with my setup as when I restarted the machine the wired connection started working but the connection was lost again as the print head moved and the connection was lost again. This is a long walk but an important reminder to check the thing you least expected to be wrong: the ethernet cable. I pulled out a tester and there was a loose lead in one of the connectors. I swapped cables and the connection now works flawlessly.