Troubleshooting Time Machine on Synology RT2600ac Router

It is better to use HFS+ and Big Sur will create an APFS format Sparsebundle on the disk.

The Mac OS cannot write directly to Network drive.. everything goes through the firmware of the Synology, so it will always create a Sparsebundle anyway.

Tesserax posted some details that is worth a quick read.. please see this thread.

https://discussions.apple.com/thread/252782504

Now I am also wondering if the old Time Capsule drive can be used for anything if the router can be turned off.

If you add another new router to your network, the Time Capsule can be connected to the new router using a wired Ethernet cable connection and configured to operate in Bridge Mode, so the routing functions are turned off, but the Time Capsule will still act as a network drive.

If you don't need the WiFi service from the Time Capsule......(it can still provide a WiFi signal in Bridge Mode).......you can turn off the WiFi as a separate action and use the Time Capsule as a simple wired network drive.

Is the only way to configure the old Time Capsule by WiFi?

Connect an Ethernet cable from your Mac to one of the three LAN Ethernet ports on the Time Capsule

Open AirPort Utility and click on Other WiFi Devices

Select Ethernet, not WiFi

Depending on how the connection priority is set up on your Mac, you may need to turn off the WiFi on the Mac to make Ethernet active. In other words, if your Mac is now set to prioritize WiFi (Apple laptops for the last 5 years or so are set this way by default)......the connection will be over WiFi even if an Ethernet cable is connected.

If you want to see how your Mac is currently set up connection priority wise, or if you want to change the order connection priority.......

Open System Preferences on your Mac

Open Network

There are 3 small icons at the bottom of the connection list

Click on the third icon from the left

Then click on Set Service Order

If both WiFi and Ethernet are connected and you want the Mac to default to WiFi, then WiFi needs to be at the top of the list

If both WiFi and Ethernet are connected and you want the Mac to default to Ethernet, then Ethernet needs to be at the top of the list

Click and drag the connection that you want as the priority to the top of the list if you need to make any changes

Don't have a Synology router here to test at this time, but If you are running Big Sur on your Mac, all bets are probably off.

Up until Big Sur, Time Machine required a hard drive formatted in Mac OS Extended (Journaled), but Apple changed the format of Big Sur Macs to APFS, which Time Machine wants to use to back up the Mac.

I would be surprised if the Synology router supported APFS and don't know if Time Machine will happily back up to a hard drive formatted the old way before Big Sur appeared on the scene.

How is the hard drive formatted? If you are not sure, temporarily connect the hard drive directly to your Mac and the drive icon will appear on the desktop

Right-click on the drive icon, then click on Get Info

Look for Format in the info window that appears. What is the format?

Note......Big Sur / Time Machine will back up to a Time Capsule, which is formatted in Mac OS Extended (Journaled), but there are some tricks going on behind the scenes. That may be the way to try to set up the hard drive connected to the USB port on the Synology router. We'll know more when you can confirm how the hard drive is formatted.

Was the USB formatted HFS+.. it cannot be APFS which is Apple only..

I have used a Synology router with USB HFS+ and Time Machine which worked really well.. but that was a while ago and before the massive changes Apple made at Catalina and even more so .. Big Sur.. where things got really hairy.

We do need to know what OS you are using??

Also did you update the RT2600AC to the latest firmware.. that is important.

I don't use big sur yet.. and my newest Mac is only able to use High Sierra.. so that might be a limitation.

Otherwise I am happy to create a more precise HowTo document.

You also might find some other sites like youtube have good video on setup of time machine on synology NAS which is very similar to the router.

I have found that it is better to first format the drive in Mac OS Extended (Journaled) and then let Time Machine reformat the drive before it starts the first backup. This will happen automatically.

If the drive is "local", meaning that it is connected directly to your Mac, then Time Machine will automatically format the drive in APFS (Case Sensitive) before the backup will begin.

If the drive is "network", meaning that it is connected to the USB port on the Synology router, then Time Machine will not change the format of the drive.......but it will format the sparsebundle on the drive containing all the backups in APFS.

Something is wrong if you do not have an option to format the drive in a number of different options. In Disk Utility, you have to format the top level of the drive......not the "container" or the name of the drive under the "container".

Finally, Time Machine backups to a network drive have not been all that reliable over the past few years, and things have not improved with Big Sur. My recommendation.......if you want to use Time Machine......connect the drive directly to your Mac.

When I formatted a spare hard drive here a few weeks ago in Mac OS Extended (Journaled) and connected the drive to the USB port on an AirPort Extreme, I set up Time Machine in the normal way.

I did not know that the sparsebundle file......containing all the backups.......was automatically formatted in APFS (Case Sensitive) until I did some checking and experimenting trying to help another user who was having problems similar to yours.

If you want to connect the drive to the Synology router, the only way that things will work.....in my opinion......is to format the drive in Mac OS Extended (Journaled). Then, let Time Machine take care of the rest for you.

I assume that you are aware that you cannot "swap" the drive back and forth from the Synology router to your Mac and vice versa. Time Machine will try to start a new complete backup if you do this......because Time Machine backs up to a "local" drive differently than it does to a "network" drive.

The overheating issue on your Time Capsule is very likely being caused by an internal cooling fan that is clogged with dust. I've had the same issue on 2 Time Capsule here when they were both about 3-4 years old. Replacing the fan solved the issue. It's a $25 part, but taking the Time Capsule apart and putting it back together was a really difficult task. Apple never designed the product for service.

Thanks for response and solution.

The 150MB is hidden boot partition.. so I would say the issue is how Mac is formatting the drive.. And it might be Big Sur because I am sure I formatted my drive on Mac HFS+ before using it on the Synology router. Big Sur is throwing all kinds of curve balls into the works.

The choices were FAT32 and AP4.

AP4?? I would expect EXT4 .. I will need to look up AP4.

And yes I do agree the layout of the Synology firmware is somewhat messy.. the online help is very good though.

https://www.synology.com/sv-se/knowledgebase/SRM/help/SRM/ControlPanel/storage_storage

I checked with my neighbor........who did replace an AirPort Extreme with an attached hard drive with a Synology router and he has not had any issues with Time Machine backups. He added a new hard drive when he upgraded his Mac to Big Sur to start backups that way.

Because he did not even know that Big Sur changed the drive format for Macs, he went ahead and formatted a new hard drive the same way that he has done in the past using Mac OS Extended (Journaled).

Time Machine took care of everything else automatically. He just discovered by examining the sparsebundle file that holds all the backups that the sparsebundle was formatted in APFS (Case Sensitive), although the hard drive itself remains formatted in Mac OS Extended (Journaled).

So, his backups are formatted differently than the hard drive, a fact that he did not know. Frankly, this makes things more complicated and with that come more chances of errors.

If it works for you, that's great. If I were trying the same thing, I would also connect a hard drive directly to my Mac(s) every day or so and back up using Time Machine that way as well. It's a simpler and much faster process when Time Machine backs up to a "local" drive.

Note.....my neighbor only uses the hard drive that is connected to his Synology router for Time Machine. He does not use the drive for any other type of file storage, sharing, etc.

I'm not trying to defend Synology's support group, but to be fair, nothing has changed for Time Machine. You still format the hard drive the same way that you did before Big Sur and then let Time Machine take care of everything else.

Your mistake......and mine......was thinking that since Apple changed the format of the hard drive on Big Sur Macs, that a backup drive needed to be formatted the same way.

As a test, I am going to format a spare hard drive in APFS (Case Sensitive) and connect it directly to my Mac to see if Time Machine will back up to the drive that way. Will report on the results later today.