Sudden loss of DNS resolution

[weirdcrap]

UnRAID v6.8.3

 

Diagnostics and the previous two system logs capturing roughly my last 30 days of uptime: node-diagnostics-20201129-0852.zip

 

A very strange issue I have just now started experiencing. Twice in the last 48 hours UnRAID has completely list its ability to resolve DNS names without a reboot of the server. All attempts to ping by name result in "name or service not known". UnRAID is unable to resolve any names for update checks and the like. Pinging by IP address works without issue and my wireguard sever continues to provide access to the system.

 

 

I have made no recent changes to network setup or DNS. My network settings are statically configured and I utilize 3 upstream DNS servers which all remain pingable during this outage: 8.8.8.8, 1.1.1.1, 8.8.4.4

 

When this issue occurs I can get into other devices on the network and they can resolve names just fine so this is something exclusive to my machine it would appear.

 

If you look at my syslog from 11/28-11/29 (included in the zip above) you will see I rebooted the server and after a few minutes DNS resolution started working again and I was able to update some plugins and whatnot.

 

Nov 28 11:49:12 Node emhttpd: cmd: /usr/local/emhttp/plugins/dynamix.plugin.manager/scripts/plugin update fix.common.problems.plg
Nov 28 11:49:12 Node root: plugin: creating: /boot/config/plugins/fix.common.problems/fix.common.problems-2020.11.28-x86_64-1.txz - downloading from URL https://raw.githubusercontent.com/Squidly271/fix.common.problems/master/archive/fix.common.problems-2020.11.28-x86_64-1.txz
Nov 28 11:49:12 Node root: plugin: checking: /boot/config/plugins/fix.common.problems/fix.common.problems-2020.11.28-x86_64-1.txz - MD5
Nov 28 11:49:12 Node root: plugin: running: /boot/config/plugins/fix.common.problems/fix.common.problems-2020.11.28-x86_64-1.txz
Nov 28 11:49:13 Node root: plugin: running: anonymous
Nov 28 12:49:00 Node kernel: veth375a643: renamed from eth0
Nov 28 12:49:00 Node kernel: docker0: port 1(veth20db4d4) entered disabled state
Nov 28 12:49:00 Node kernel: docker0: port 1(veth20db4d4) entered disabled state
Nov 28 12:49:00 Node kernel: device veth20db4d4 left promiscuous mode
Nov 28 12:49:00 Node kernel: docker0: port 1(veth20db4d4) entered disabled state
Nov 28 13:51:25 Node kernel: mdcmd (47): spindown 4
Nov 28 13:51:26 Node kernel: mdcmd (48): spindown 6
Nov 28 13:51:26 Node kernel: mdcmd (49): spindown 7
Nov 28 13:51:26 Node kernel: mdcmd (50): spindown 9
Nov 28 13:51:52 Node kernel: mdcmd (51): set md_write_method 0
Nov 28 13:51:52 Node kernel: 
Nov 28 14:00:43 Node kernel: mdcmd (52): spindown 2
Nov 28 14:01:36 Node kernel: mdcmd (53): spindown 1
Nov 28 15:21:54 Node kernel: mdcmd (54): set md_write_method 1
Nov 28 15:21:54 Node kernel: 
Nov 28 17:25:38 Node kernel: mdcmd (55): spindown 1
Nov 28 17:25:48 Node kernel: mdcmd (56): spindown 2
Nov 28 17:25:50 Node kernel: mdcmd (57): spindown 9
Nov 28 17:25:53 Node kernel: mdcmd (58): spindown 7
Nov 28 17:25:56 Node kernel: mdcmd (59): set md_write_method 0
Nov 28 17:25:56 Node kernel: 
Nov 28 19:40:22 Node kernel: mdcmd (60): spindown 4
Nov 28 19:52:48 Node kernel: mdcmd (61): spindown 8
Nov 28 20:41:07 Node kernel: mdcmd (62): spindown 6
Nov 28 21:27:50 Node kernel: mdcmd (63): spindown 9
Nov 28 23:20:56 Node kernel: mdcmd (64): spindown 4
Nov 28 23:27:19 Node kernel: mdcmd (65): spindown 5
Nov 28 23:41:38 Node kernel: mdcmd (66): spindown 7
Nov 29 00:00:01 Node Docker Auto Update: Community Applications Docker Autoupdate running
Nov 29 00:00:01 Node Docker Auto Update: Checking for available updates
Nov 29 00:00:02 Node Docker Auto Update: No updates will be installed
Nov 29 00:15:03 Node kernel: mdcmd (67): spindown 8
Nov 29 00:43:31 Node kernel: mdcmd (68): spindown 2
Nov 29 01:00:01 Node root: Fix Common Problems Version 2020.11.28
Nov 29 01:00:01 Node root: Fix Common Problems: Error: Unable to communicate with GitHub.com
Nov 29 01:00:01 Node root: Fix Common Problems: Other Warning: Could not check for blacklisted plugins
Nov 29 01:00:12 Node root: Fix Common Problems: Other Warning: Could not perform docker application port tests
Nov 29 01:00:12 Node sSMTP[31740]: Unable to locate smtp.gmail.com
Nov 29 01:00:12 Node sSMTP[31740]: Cannot open smtp.gmail.com:465
Nov 29 01:01:11 Node kernel: mdcmd (69): set md_write_method 1

Everything was great until 1AM when FCP wanted to run and was unable to resolve github.com again... I see nothing between those two events that explains my sudden loss of DNS or why this seems to be all of a sudden happening daily.

 

I'd love some help in figuring this out as it brings my server and dockers to a grinding halt with so many parts depending on name resolution.

 

EDIT: In the time it took me to draft this topic I have lost DNS resolution again. I'm at a loss as to what has suddenly changed to cause this...

 

EDIT2: hmm it almost seems to be related to docker? I stopped the dockers and docker service and now its back up? I'm honestly just grasping at straws here though, I can't seem to find a rhyme or reason yet. Bringing docker back online doesn't seem to immediately break it.

 

UPDATE: Well It's now been 48 hours with no issues...I still have no idea what caused this but it seems to have resolved itself....

Edited December 1, 2020 by weirdcrap