File access becomes painfully slow if NAS is not able to access internet

[jdholbrook33]

I have a NAS server in the living room. I use it to store movies and music.
It's a simple server and has been running without issue for at least 5 years and I use it almost daily.
Well, yesterday the cable guys worked on the neighbors cable and that knocked my cable out.
Ok no problem I'll just play some music off the server while I clean house.
Wrong!!! The access to files was so painfully slow and erratic that I couldn't play music.
Later I tried to play a movie just before bed. Same story, took forever to even give a file listing.
Selecting a move that I've watched many times already was painful. It took forever to load then after around 20 minutes it just locked up.
Something that's never happened before.
Later that night the internet was back briefly. The server was acting normal again.
Then around 10pm the internet was out again, same story with the files. Couldn't watch a movie or play music.
What gives???

My home network is:
ASUS wifi router setup as the DHCP server and directly connected to my Motorola Surfboard modem.
I have an 8 port switch feeding the house with outlets in each room and two in the living room.
I can stream music or movies from my windows machine and all is fine. Just the NAS server is very flaky when not connected to the internet.
This gives me a very bad feeling.

 

[jgreco]

It's probably not the NAS server. Many of us run FreeNAS with zero internet visibility. Works swimmingly well.

It is most likely to be something related to hostname lookups or service discovery. The ASUS "router" is suspect as many of these devices lose their minds a little bit when the expected upstream Internet is not available, but there are a bunch of possible variables at play and it isn't clear what's happening to you.

Is the NAS configured to use DHCP (bad)?

 

[jdholbrook33]

Yes, the NAS is on fixed IP along with most of the equipment on my network. Wifi devices get DHCP and some of the PCs get DHCP.
My network is:
modem --- PiHole --- ASUS --- 8 port --- devices including a few more 4 or 8 port switches.
192.168.1.XXX, DNS points to PiHole

Can you give more details on what you mean by Asus losing it's mind?
I may be able to work around it.

Thanks,

James

 

[jgreco]

Well, most of these devices are based off of open-source software offerings, and firmware manufacturers sometimes do aggressive things like "restart entire network stack if internet is down", which can cause interesting behaviours such as the DHCP daemon being constantly restarted, service discovery being constantly restarted, nameservice daemon being restarted, etc. This can cause a wide variety of unexpected issues, such as clients not obtaining an IP or better yet multiple clients ending up on the same IP, or FreeNAS trying to do DNS lookups on connections and having this fail because the nameservice daemon is flapping or returning SERVFAIL, etc. You have an additional complication in the form of the PiHole, which may be fooling the NAT gateway into believing that the Internet is up and running when it isn't. There are lots of potential sharp edges and the thing to do is to offline your network deliberately and replicate this, then do a root cause analysis and remediation.