Problem using Time Machine with Synology DS218+

[jhmiii]

I've had a Synology DS218+ for a few years. It is used to back up two computers via Time Machine. The only problem I have experienced is when the power goes out and the Synology reboots. Sometimes it arrives back on the network with a new address. In the past the addresses only varied between 192.168.0.2 and 192.168.0.4. I was able in these cases to reset the DS218 address back to 0.2 and then Time Machine would find the drive and all was well. The power went out two weeks ago and now the DS218 has an address of 192.168.4.44. I've been unable to change this successfully to 0.2. When I attempt to change it the DS218 can no longer be found by either the Synology app or via their web service. (Is the third number the gateway? Maybe it can't be changed? Clearly, I don't really understand these addresses!)

So I decided to just change the disk that Time Machine uses. Time Machine preferences sees the new disk and also recognizes the backup file on the disk. It correctly asks me if I would like to use this file as a replacement for the file at the previous address. I say yes and it asks for a password. The password for this sparsebundle is in Keychain, so I enter it. Of course it is not recognized!! I realize that without the password I can't access this old sparsebundle and must begin backups from scratch.

Finally, I am getting to my question. What is the best way to keep this from happening in the future? Is there some way to get Time Machine to recognize the disk and not the address of the disk? Is there a way to more effectively control the assigned address? Should I just purchase a UPS and hope it keeps the DS218 from rebooting?

I appreciate any and all input.

John

Mac Book Pro 15" 2016
OS 10.14.6

 

[MacInWin]

John, from your description, it sounds like the DS218 is not attached to your network but to a neighboring one. The 192.168.x.y range of IP numbers, where x and y are from 0 to 255, is set aside for internal local area networks. But the internal network also is normally set up in your router to have just one subnet, 192.168.0.y in your case. So, when the DS218 reboots, what happens is that it asks the router for an IP number and YOUR router should provide something in the 192.168.0.y range. The fact that it is showing up with 192.168.4.44 says that the router it is attaching to is issuing IPs in the range 192.168.4.y. And that is why you then cannot attach to it, change the number or get to it through the web. It's not on YOUR network.

How have you, in the past, changed the assigned number to 192.168.0.2? I ask because if you are manually setting it, there is an excellent chance that the router also assigned the same number to some other device, which will also then cause issues with connecting and using the DS218.

How is the NAS attached to the router? I am presuming, from your description, that the connection is wireless. Can it be attached with an Ethernet cable? That would prevent it from connecting to a neighboring network and getting a number that isn't in your network.

The UPS is an excellent idea in any case. Given the inherent fragility of sparcebundle backups, if the power fails during a backup in progress, you'll easily lose the entire backup and have to start from scratch, possibly on both backup sets.

 

[jhmiii]

Jake, Thanks for the detailed response. I forgot to mention that we recently got a new modem from Spectrum, if that makes any difference. The DS218 is connected via ethernet to the Eero wifi and the Eero via ethernet to the modem. I don't know of any neighboring network the DS218 could be connecting through.

Johhn

 

[Raz0rEdge]

If you are running DSM 6.2.3 (or around there), go to Control Panel->Network and choose the Network Interface tab. Either Lan1 or Lan2 will be "Connected", select it and click on Edit on top.

You now want to choose "Use Manual Configuration" and enter an IP address in there, I would use a higher IP address, for example, on my DS412+ I use 192.168.0.200.

For the rest, you'll use 255.255.255.0 as subnet mask, and 192.168.0.1 for gateway and DNS server.

Now, your NAS will stick to that IP address across reboots.

 

[jhmiii]

Ashwin, Thanks. I will give it a try. Gateway and DNS server should be the same?

 

[Raz0rEdge]

Ashwin, Thanks. I will give it a try. Gateway and DNS server should be the same?

Gateway is your router's IP address and DNS should be the same and the router will redirect to your ISP's DNS. You can also bypass that directly and use other public DNS' like Google's 8.8.8.8 or whatever.

 

[MacInWin]

You now want to choose "Use Manual Configuration" and enter an IP address in there, I would use a higher IP address, for example, on my DS412+ I use 192.168.0.200.

If you choose to do this, go to the router and under the DHCP settings, block the server from issuing that number to another device. Just using a high number and hoping the server won't get there is a good way to end up with trouble later on.

 

[Raz0rEdge]

Fair enough and yes that's a needed change to avoid IP address conflicts.