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Restoring a backup on another unit of the same model

Discussion in 'Asuswrt-Merlin' started by Tchirou, Jan 15, 2020.

  1. Tchirou

    Tchirou Occasional Visitor

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    Hello
    I am running the firmware 384.13 on a Asus AC68u. One of the antennas is broken.
    I was wondering if I could buy another AC68u and restore on this one a backup of the old one safely.
    Sorry if it seems a noob question, I have read the pinned post and did a search but I haven't found an answer
    Many thanks
     
  2. oso2276

    oso2276 Regular Contributor

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    Due to differences in hardware, Mac address and other stuff, it most likely will not work.

    Edit: update the recommendation based on other people's feedback
     
    Last edited: Jan 15, 2020
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  3. Tchirou

    Tchirou Occasional Visitor

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    Many thanks for this fast reply. I will buy a new one on amazon and test. If it doesn't work, I will send it back.
    I will report back for potential future users interested in this piece of info.
     
  4. ColinTaylor

    ColinTaylor Part of the Furniture

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    The advice given on these forums (many times) has always been "No". The backup files are only meant to be used for restoring the device on which they were created. That said, if you can guarantee that the new hardware is exactly the same revision as the old and the backup is from exactly the same firmware version you'll probably get away with it.

    On the other hand, the initial setup is something you only plan to do once so you might as well do it properly and set it up from scratch. That way if you experience any "strange" problems in the future you can be sure that it's not a problem carried over from the previous router.
     
    Last edited: Jan 15, 2020
    jsbeddow, L&LD, Tchirou and 1 other person like this.
  5. oso2276

    oso2276 Regular Contributor

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    Never the less I have moved settings with backup,restore on same model/firmware devices with no issues. I would say he has great chance of success if he gets same hardware and firmware

    Enviado desde mi moto g(8) plus mediante Tapatalk
     
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  6. Tchirou

    Tchirou Occasional Visitor

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    @ColinTaylor
    Indeed, I think that I will take screenshots of all the settings and If I encounter some problems in the future, I will reset and set it up manually.
    But It's good to know that it may possible that the restore works flawlessly, given oso2276's past experience

    Thank you both for your input
     
  7. Ronald Schwerer

    Ronald Schwerer Senior Member

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    I know the MAC addresses are stored in both the CFE and NVRAM. I assume the MACs and many other parameters are copied from the CFE (/dev/mtd0) and stored into NVRAM (/dev/mtd1) when a device is initialized during setup. If you restore the settings from another "identical" unit, won't there be a mismatch?
    Furthermore. on a 68U there are about 20 radio fine-tuned parameters in the CFE that are specific to the individual unit's hardware. These are also copied into NVRAM only when firmware is initialized during initial setup (or after a factory reset). The side-effect of using these parameters from another unit may, or may not be noticable by a user. But the radio performance will not be optimal.
     
    Last edited: Jan 15, 2020
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  8. Tchirou

    Tchirou Occasional Visitor

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    Well it's too technical for me now :D
     
  9. oso2276

    oso2276 Regular Contributor

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    Noted. Then I think it worked for me just by Chance. Thanks for the insight

    Enviado desde mi moto g(8) plus mediante Tapatalk
     
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  10. Ronald Schwerer

    Ronald Schwerer Senior Member

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    You asked the question. Sorry it isn't just yes or no answer.
     
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  11. Ronald Schwerer

    Ronald Schwerer Senior Member

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    Yes, it might work fine. I've done it myself once. I'm not sure about side effects. It would be interesting to see which MACs (all 3) get used.
    Worst case is you need to do a factory reset, so you're no worse off than doing it the right way.
     
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  12. Tchirou

    Tchirou Occasional Visitor

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    It's just that when you wrote "If you restore the settings from another "identical" unit, won't there be a mismatch?", I didn't know if it was a rhetorical or actual question, hence my answser ;-)
     
  13. Ronald Schwerer

    Ronald Schwerer Senior Member

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    Ah, I see. And it was sorta rhetorical, since I'm not sure if it will be a problem. Just something to be aware of if things aren't working as expected.
     
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  14. ColinTaylor

    ColinTaylor Part of the Furniture

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    Yes, this is the potential problem. The backup file is a complete dump of the NVRAM partition and that includes many variables that are not only specific to that router's hardware but also unique (e.g. MAC addresses, WPS PIN, serial number, etc.).

    There was a case reported in these forums where a member bought a second router of exactly the same model and restored a backup from his first router to his second. He then changed its IP address and configured it as an additional access point on his network. He then found the whole of his LAN stopped working when he plugged it in. The reason was that he had effectively duplicated the MAC addresses used by the router onto the access point which is obviously going to break his network.

    However with the above said, I recently reviewed the source code with regards to this. The backup files still contain all the data, however the restore process is selective and tries to only restore device independent variables. The way the MAC addresses are assigned is also slightly different now. I don't know whether this is a deliberate attempt to make the backup files more transferable or just a coincidence. Either way, given the infrequency of having to setup a new router I prefer to do it manually just for my own peace of mind.
     
  15. Tchirou

    Tchirou Occasional Visitor

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    Thanks for this info. In my case, I don't want to add it to the network but just replace it so maybe it will be smoother, independently of the possible optimization
    I will let you know if it works okay
     
  16. EventPhotoMan

    EventPhotoMan Very Senior Member

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    Why wouldn’t you just screw the new antenna on to the old router, if it’s the same model... solves all the problems.
     
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  17. Tchirou

    Tchirou Occasional Visitor

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    I think I remember it was broken on the routeur side but I am not so sure now, I will check tonight at home.
     
  18. dosborne

    dosborne Senior Member

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    Worth mentioning that if you are to try this, be warned it may cause some very hard to detect issues. Word of advice, ensure to take a backup BEFORE trying it so that you have a potential recovery option.

    Personally, I always create backup folders for firmware, config files, etc for all my devices (where possible of course). Configuration files get renamed to clearly indicate the device, the date and the firmware version. Before anything significant, such as a FW update, I always save a new configuration file, perform the up/downgrade, then save another configuration file. Often I create a text file with the same name as the configuration file where I place notes about what settings I changed. For some of my devices, I literally have hundreds of historical configuration files. Rarely actually required, but worth gold if you ever need to rely on one.
     
  19. Tchirou

    Tchirou Occasional Visitor

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    Hello all
    I checked the router and indeed it was broken on the router side like I remembered. But I tried to force and unscrew the top and at my surprise, the plastic bit came so I just need to change the antenna :D
    Thanks @EventPhotoMan for the good ol’ advice, I hadn’t tried properly and just used 2 antennas for almost 2 years now
    I guess we won’t know for now if the restore would have worked flawlessly

    @dosborne
    Good general advice, I myself am a backup addict too :D

    Many thanks to all for sharing on this, even if we didn’t get to the bottom of it, I am sure @oso2276 past experience and your opinions will help someone in the same situation in the future

    Please have a very good day
     
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  20. laracroftonline

    laracroftonline Occasional Visitor

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    I wouldn’t say directly no, because if the hardware is identical you only have to make sure the firmware is identical and then you can restore your backup without issues. People in here say far to quick no is what i have seen while it’s not always a no just make sure both routers are the same in hardware as in firmware and you are good to go
     
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