AVM FRITZ!Box 7362 SL to 7520 upgrade + 7530 unlocking (#P39)

Quick reminder/PSA: Router patch week in every parent’s basement starts in a dozen days. Be prepared!

Not actually sure what type of…internet-free telephone service box thing my mom is using in the inherited farm house, but at my place, I needed an upgrade. Until earlier this week, an AVM Fritz Box 7362 SL (the cheapo 1&1 branded one) provided service. Bought that sucker 8 years and a month ago and it’s running just fine – except for the fact that it is considered EoL by AVM. That however is debatable, since on the one hand AVM announced EoM (end of maintenance) and EoS (service) dates for that box type to be June and December of 2019 respectively, but on the other hand nowadays no longer states exact dates for any product and has released FritzOS 7.13 for it just last month. Still, chances are this is the very last update for it – more current routers are running version 7.29 already. Moving to third party software (OpenWRT once again comes to mind) isn’t an option until they got full modem (duh!) and DECT support. Freetz builds aren’t really addressing the no-more-updates issue.

So I moved on to the next shady branded model without an un-branded retail version available – the 7520. Equally shady sourcing aside, this is the closest match to the old budget model and just about perfect. Same 2x 1G + 2x 100Mb ports* (I only need one 1G uplink to the PoE switch), USB* for charging the DECT phone, DECT (you know, for the DECT phone…and the four central heating thermostats), VDSL Vectoring support for 100Mbit+ connectivity (7520 does support Supervectoring which is available for a tenner per month extra, but does not add any upload speed), TAE jack for the printer with fax module. That’s about it. It no longer has 3×3 MIMO WiFi support for n (one major selling point for the 7362), but supports WiFi ac 2×2 instead – since I’m using an external access point (#P16) anyway, that’s disabled by default and I don’t really care.

Why is that good enough for a blog post? Well, there’s two asterisks in the text above. The 7520 offers USB 2.0 and mixed 1G-1G-100M-100M LAN ports. That’s dubious since as I said, this is a branded-only box, and it uses the exact same PCB layout as the 7530. That one, however, does offer USB 3.0 and four 1G ports. The 7520 does not, despite the fact that the LAN transducers are the same for all ports and the USB jack is physically a USB 3.0 unit with 9 pins (+2 for mounting). People have noticed this before, so I’m not the one that brings the good news.

I just want to confirm that this is still a viable software option and AVM has not (yet) decided to lock it as of FritzOS 7.29. They do however enforce the 1&1 branding per volatile environmental values in their bootloader, which is a bit silly, really. People are working on that, though, but apparently there’s currently no safe way to change these values permanently. One can upload firmware that doesn’t read the branding and just displays stock menus and skips the stupid 1&1 (or Vodafone, or…) install wizard.

Well, procedure is as follows:

Set up your Fritz Box, grab a LAN cable and a suitable computer. Download the 7530 recovery utility matching the currently installed FritzOS version. Download a random FTP software if not already installed. Set the computer LAN port to a 192.168.178.x static IP (I used .100) since the bootloader will not use any other IP range the box can be moved to (192.168.0.x for me). Plug in the cable, open the utility (does run in WINE as well!) and follow instructions until it displays an error. This is the quickest way to get into the bootloader menu.

Searching FRITZ!Box 7530 at:
One system found! - Detecting the current version.
Version successfully detected!
    Hardware:	FRITZ!Box 7530
    Bootstrap:	10733
    Firmware:	175.07.29
FRITZ!Box 7530 firmware is incompatible with the recovery firmware

Now connect to the IP that is included in the error message, usually Username is adam2, password is adam2. Dial into the box and run the SETENV HWRevision 236 command (depending on software, it might need quote SETENV HWRevision 236). This sets the hardware to 7530 temporally – it will default back to 247 on the next power cycle. It is not necessary to set ProductID or firmware_version since it will have no effect (sadly…). Do not change HWSubRevision. Exit the FTP tool (important!). Now run the utility again but do not power cycle the box, it already is at bootloader stage. It will now accept the 7530 hardware and start flashing. Once all partitions are set, it’ll reboot and come up as 7530 – sort of. :good:

Issues with that setup:
1) Those steps are necessary again in order to recover from a major brain fart, since the utility will see hardware 247 on next boot and refuse to flash 7530 firmware to it. However, that is exactly how to revert back to 7520: Run the 7520 recovery tool and it will gladly accept ID 247 in order to flash back to stock 7520 software.
2) Deep down, the update check path is built with those bootloader variables regardless of software running. That means the update check will always yield a new software update since it differs from the currently running packages, but the update will fail as it downloads 7520 software. Disable update checks and download new 7530 images manually, as they will be accepted by the manual firmware upload page without issues.
3) For similar strange reasons, the DECT (and probably the WiFi?) net names are using 7520 as well, e.g. any DECT phone will pair with a 7520 base station. This identifier can be changed in the menu manually.
4) The box will still be black instead of white and red :roll: (I prefer black, although the red one goes faster…)

As for the “missing” features, check those two screenshots:

So those are present, and while I haven’t checked the USB yet, LAN 3 and 4 now offer full 1Gb/s of throughput if one desires:
e1000e 0000:00:19.0 eth0: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx

instead of

e1000e 0000:00:19.0 eth0: NIC Link is Up 100 Mbps Full Duplex, Flow Control: Rx/Tx
e1000e 0000:00:19.0 eth0: 10/100 speed: disabling TSO

Magic, isn’t it? Software that adds hardware… :twisted:

Now for the boring bits, speed and power consumption:

DSL sync speeds – click for full size. Those haven’t changed all that much, in part because all units basically max out the line limits set by the provider. The newer box(es) sync slightly higher but do not offer additional speed (say, at speedtest.net), so those couple percent do not manifest in a real-world boost. Results are always in the 100 Mb/s (down) and 35 Mb/s (up) range, with a couple percent deviation depending on day, time of day and luck, I guess.

They also display a guess on SNR both ways and it is just that: A guess. Bonus for the 7530: It offers an estimate on the telephone line length. That wankery is, of course, not available on the plebeian 7520.

So while speed is no reason to upgrade on my specific situation, maybe power consumption is? After all, routers literally run 24/7. Luckily, my setup with switch (and AP) connected to the router allows for an easy baseline measurement without unplugging literally a dozen devices. So I’ve made a backup with the 7362 and restored it in the 7520/7530s. That shouldn’t be possible due to the former being unbranded avm and the others being 1und1, but it works just fine. I’ve set LAN port 1 to Gb/s and the others to 100Mb/s, disabled WiFi (on by default on recovery, got me once!) and waited for DSL sync. DECT was active but I wasn’t on the phone. All boxes were supplied by my HP6644A at 12.1V at some four meters of leads, so let’s assume 12.0V at input.

Fritz 7362 idles at 440mA and doesn’t really use all that much more when running speedtest.net, maybe 460mA
Fritz 7520 starts at 450mA and reduces usage to 310mA after a minute or so. Guess there’s more background stuff that isn’t executed all at once and needs a bit of time to die down. High traffic uses in the order of 350mA.
Fritz 7530 does the same and sometimes dips below 300mA.

No, it’s not the LED brightness settings that are available in the 7530, and turning off the media center features also doesn’t save anything. WiFi however consumes quite a significant bit if activated, around 60mA for the 2.4G band and 80mA for the 5G band, both at idle (100mA+ additional consumption if active, e.g. benchmarking via WiFi of the router instead of WiFi over AP).
Technically that means the newer box offers the same power consumption as the old one, but with free WiFi. In my case with the external AP, this is a downgrade from 5.3W to 3.7W, a 30% reduction in power consumption. While Germany has world-leading electricity prices and my tariff went up 10% two weeks ago, this only means 46kWh vs. 33kWh or 13€ vs 9€ annually. Worst case (or should I say best case?), this saves 4€ per year, so it pays itself off in just 10 years without additional price hikes (YMMV). While that’s not a no-brainer in terms of savings, it’ll certainly please our new Green overlords. Plus I’ll donate the box to somebody else, so it won’t go to the skip immediately and even has the chance to replace something older and more power-hungry. And I got a new box that still receives updates. Hooray.

Would I recommend that for anyone tech-savvy? Heck yes. At 40-60€ delivered vs. 90-110€ of a regular 7530 on eBay (or 160€+ from retailers!), the savings are clearly worth the couple of minutes needed for setup. I probably wouldn’t run this unattended and three hours away in case someone manages to enable update notifications, but for those scenarios even the base 7520 will do just fine. Sure, if you need the bigger WiFi marketing numbers of the higher end models, go for it, but as a cheap, easy-to-operate, low-power and hopefully reliable WiFi and LAN router, this thing is the bomb.

Other DSL models (not) to consider:
7272: EOL despite 12/2021 v6 firmware update
7360V2: EOL despite 12/2021 v6 firmware update
7362SL: Well, I just upgraded away from that one…even if it has v7 software!
7390: EOL despite 12/2021 firmware update, not even v7 software (being the former flagship model!)
7412: EOL despite 11/2021 v6 firmware update
7430: Nice but no Gigabit ports, v7.29
7490: Nice, v7.29, ~70€ used
7520: Nice! :D
7530: Slightly nicer…
7530AX: Nice, v7.29, 140€
7560: Nice, v7.29, no Supervectoring, 60€
7580: Nice, v7.29, no Supervectoring, 80€
7581: EOL at v7.15, 100€
7582: Somewhat EOL, not patched beyond v7.15 yet, 80€
7583: Nice, v7.29, 200-250€ (rare)
7583 VDSL: Nice, v7.29 250€+ (rare)
7590: Nice, v7.29, 150€
7590AX: Nice, v7.29, 250€

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I have 7520 and lan3 and 4 are locked on 100mbit. Can You help me with this? :) thanks.

Last edited 1 year ago by Tim

thanks for this article. I enjoyed reading and was very much impressed about your english – although I somehow felt that you are Not native.

I just bought an 1und1 7520 today and I plan to „Upgrade“ it to a 7530.

One question about your article: What do you mean by „I probably wouldn’t run this unattended and three hours away in case someone manages to enable update notifications, but for those scenarios even the base 7520 will do just fine.“?? Why wouldnt you run that upgraded 7520 in everyday-use? Whats the Problem with the Update notifications?

I would be very happy about an answer – no matter if in English or German.


Do you have any evidence of such a chain of unfortunate events? Or is it just a fear you have virtually every time you install another foreign firmware?

I wouldn’t upgrade for USB 3 or 4 gigabit ports, but for the more recent FritzOS. The latest FritzOS of the 7530 supports wireguard.

I found an article where even heise tells about this „Hack“:

So I think the Hack is serious.

Last edited 1 year ago by Flo

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Thks for the nice instructions, worked on the spot; I happen to have more or less the same setup – also using a 7362sl so far, but now moved beyond the 100 Mbit, so needed super vectoring. I would not have been brave enough to use wine for the tool :-=


Update: Updated in my 7520 to to the 7530… and now I realised I have the ‘Typ B’ version, means that the DSL chip is not supported by the 7530 firmware – but the 1000 Mbit switch is…. I’m thus like TIM also looking for a way to keep the 7520 firmware, but to use the driver of Switch from the 7530. If anyone has an Idea, I’d be curious to hear. Shame OpenWRT doesn’t supprt the DSL chip yet.