MR52 5g rx help

I have posted a couple of times regarding my problem with a Meraki MR52 5g radio.
Having tested some more, the 5g radio seems not to be able to receive. 'Channel analysis' and 'scan' for this radio show nothing (other than the same 5g radio if an SSID is enabled). Tx seems OK as wifi clients and other APs can see it, and the signal is good.
The same unit's acbgn radio seems to RX 5g OK as it can see nearby 5g APs.

I have visibly checked the 5g pigtails and their solder connections to the internal antennae. They seem secure. Is there anything else I might try? Or is it looking like this units 5g radio may be broken?
Any suggestions much appreciated.

I run a MR52 as my main AP and it works perfectly with almost a year of uptime. Using PoE from a switch.

It sounds like a hardware issue or the radio calibration data got messed up somehow.

As a sanity check, re-create your 5G network on the other 5G radio and see if it works. If it does, hardware/calibration issue. If not, then something else is messed up.

As a last resort -- flash back to MerakiOS and leave it connected to internet for 30+ min to let it update, this will reset and hopefully re-download any calibration data. Then re-flash OpenWrt and re-test.

Hope this helps.

P.S. Keep your related posts in a single thread, dont make new threads as its hard to follow. A reply will bump a thread to the top.

Thanks for the advice. I will dig it out and try your suggestions.
I, foolishly, never confirmed it working under MerkakiOS before flashing openwrt.
Any tips/advice on flashing back to MerakiOS from openwrt?

I can confirm 5g AC connection is successful via the scanning radio0 (Qualcomm Atheros QCA9887 802.11ac/b/g/n).

Hopefully you made a backup of the mtd before flashing. If not you might be out of luck.

If you didn't modify the partition table only bootkernel2 and ubi partitions need to be restored - the rest are the same.

Dont have any spare MR52 right now.. but I'll try to see if I can restore partitions to a different MR52. If successful I can upload the partitions for you and others but I suspect they are unique to each device.

No mtd backup I'm afraid to say. I did not knowingly modify the partiton table, just booted from tftpd and installed sysupgrade.
I too would expect calibration data to be unique. However, I wonder how might I verify the relevant mtd areas contain meaningful data? Would dmesg indicate if anything's untoward in that area?
Appreciate your help and sharing your thoughts.

For the radio, check dmesg and grep for radio or error

Checked a few MR52 APs.. here are the md5 hashes of each mtd and if its unique:

mtd0 44bb953df22e178e16578d65093307bd
mtd1 c61c9e17cb1004936700530fbe012fe0
mtd2 77583b00e2a8aef07a95a7c3435b7006
mtd3 bc4a3d5ae1afd6052bd70bb22b21aee3
mtd4 4cdc77f1cc3b2a52c1200af463db232e
mtd5 98acf14b787fce0fe32fb7a38074c538
mtd6 44600adfc0364427f2b92d26962fbc44
mtd7 2a632e789b932576f6e7231da1cd6e83
mtd8 [depends on u-boot version]
     65e672f4c7e7f2910a1c70e5802bbd27
     94ff0dfa10fdb429b64fd9e58f675faa
mtd9 e9e3c08adb9c193fa0521b43a89c6919
mtd10 e9e3c08adb9c193fa0521b43a89c6919
mtd11 UNIQUE
mtd12 UNIQUE

Check for mismatches. Flashing OpenWrt with sysupgrade process from wiki will replace mtd10 and mtd11

mtd9 = mtd10 = bootloader normal and backup
mtd11 = ubi = firmware partition
mtd12 = art = radio calibration

I think if you can get back to the Meraki bootloader, factory reset (push and hold button for 15-30 seconds) and let it update from the internet, it might restore everything. Then try to re-flash OpenWrt.

I have recovered at least one MR52 with this method. Others were hardware failures.

1 Like
mtd0 44bb953df22e178e16578d65093307bd  
mtd1 c61c9e17cb1004936700530fbe012fe0  
mtd2 77583b00e2a8aef07a95a7c3435b7006  
mtd3 bc4a3d5ae1afd6052bd70bb22b21aee3  
mtd4 4cdc77f1cc3b2a52c1200af463db232e  
mtd5 98acf14b787fce0fe32fb7a38074c538  
mtd6 44600adfc0364427f2b92d26962fbc44  
mtd7 2a632e789b932576f6e7231da1cd6e83  
mtd8 65e672f4c7e7f2910a1c70e5802bbd27  
mtd9 53496152d6aee6208c721ddef06440ce  
mtd10 ad79c243edd32e2dd3b499ccc1ca55e4  
mtd11 9ad6398b55f777c890b6d5980abb7390  
mtd12 dbfa254cd1b03673ce98273bc151a390  

My mtd0-8 match your checksums.

My mtd9, mtd10, bootloader and backup, differ from one another and from yours.

EDIT:
I tried resetting the unit in the hope it would boot meraki bootloader.
I'm not sure of the procedure. I tried 15+ secs and 30+ secs, with the reset depressed prior to cold start and also whilst already booted, but the unit boots to OpenWRT every time (resetted to defaults).

mtd9-11 control whats the device boots.

I think mtd9 is the backup boot partition and you can copy mtd9 -> mtd10 but you need the MerakiOS firmware on mtd11

Many thanks for the advice. I will try to track down MerakiOS and have a play. If I end up bricking it, no matter, it's now a learning tool. If I make any progress, I will update.