Hello and thank you for reading me. Sorry for my bad english.
I have a Huawei HG556a type C that I was using as WiFi repeater with OpenWrt 15.05. Yesterday I update the OpenWrt version to 17.01.6 and when I scan for networks I see this:
I have many networks in the neighbour but something happens. Any help? Thank you in advance.
For a major version upgrade you should not try to save the settings. If you did save settings, do a reset to defaults and reconfigure the router from the beginning.
Can you set up a basic AP and have it work? The "scan" function needs a working wifi interface to run the scan on.
Thank you mk24.
I did the update witaout maintaining the configuration settings. Anyway I have just reset the router and this is the wireless page I have:
After that I made a scan and the problem persists.
https://openwrt.org/toh/huawei/hg556a
Try to upgrade to 18.06.1, reset settings to defaults.
Thank you vgaetera. I did but after that I didn't see the Wireless menu:
I have been testing these days with the three models of this router and the conclusion is:
Do not upgrade this router to the latest version.
I have all three models A, B and C, and they all work perfectly until version 17.01.04. The problem is that once you update it, the calibration information (CAL_DATA) is erased and can only be recovered with a modified firmware that contains inside of it the four CAL_DATA of each of the models, three for models A and B, and one for C. The procedure to recover them is simple, follow the instructions of this topic No wifi in 18.06 with hg556a.
At the end you have installed an old version of openwrt fully operational, but ... will not let you install version 17.01.04 from Luci, you'll have to do it from CFE, and Boila!
I advise you to read the information on this router:
https://openwrt.org/toh/huawei/hg556a
The following warning is absolutely true:
Warning : Some users reported the cal_data partition got corrupted/erased after installing 18.06.1 version , leaving the wifi not usable for any firmware unless you restore again this partition. See No wifi in 18.06 with hg556a
Now I'm working on a Huawei HG622 router that has the same problem. If I get something I'll report it
Hi Willy. Sorry for the delay in the response and for my bad English. You have been accurate with the answer. This is exactly the problem. I'm doing the steps to solve the problem. I would like to say that the problem is solved but not for the moment. 
Anyway I'm so thank you. Muchas gracias. Feliz 2019.
Hi, I have (my own mistake though I believe) removed the calibration data of my hg622u by flashing hg622 (no u) firmware. If anyone has the correct calibration data, please let me know!
this person https://forum.archive.openwrt.org/viewtopic.php?id=63401 has had the same problem, my reply couldn't be recovered I guess but it was just a workaround using a dump someone posted on hg655 wiki page. It didn't work that great
Calibration data tends to be specific to each individual device, if it's lost without a backup, it's gone for good. Flashing calibration from another device of the same model might appear to help, but would lead to a miscalibrated device (and there are quite some parameters, even taking the temperature into account).
I have read somewhere that the calibration data is more specific to the type of chip, of course there is some data like the MAC that is specific to the router. If this were true, the calibration data of an RT3062 chip would theoretically be interchangeable. It is just what I am trying to do with an HG622, I want to put the calibration data of a HG556a Ver.C, but the partition CAL_DATA is write protected and I could not. In the link that I gave to correct a HG556a, the firmware was modified to be able to write in that partition, but in the current firmwares it does not allow to overwrite that partition. Which does not make sense, because if a user makes the backup of the partition CAL_DATA, then it can not dump that information because it's write-protected. The latest version of the firmware that I tested, a snapshot version, generated the partition CAL_DATA without problems, which did not make version 18.06.1, but I could not dump the CAL_DATA information obtained from the HG556a, since the partition continues protected against writing. If someone can tell me how to write the calibration data in the CAL_DATA partition, skipping the write protection, I will report the results as soon as possible.
Install kmod-mtd-rw. Then you must activate it by loading the module manually.
insmod mtd-rw i_want_a_brick=1
All the partitions will be writeable until the next reboot. Be careful.
BusyBox v1.28.4 () built-in shell (ash)
_______ ________ __
| |.-----.-----.-----.| | | |.----.| |_
| - || _ | -__| || | | || _|| _|
|_______|| __|_____|__|__||________||__| |____|
|__| W I R E L E S S F R E E D O M
-----------------------------------------------------
OpenWrt 18.06.2, r7676-cddd7b4c77
-----------------------------------------------------
root@OpenWrt:~# opkg install kmod-mtd-rw
Unknown package 'kmod-mtd-rw'.
Collected errors:
* opkg_conf_parse_file: /etc/opkg.conf:6: Ignoring invalid line: `insmod mtd-rw i_want_a_brick=1'
* opkg_install_cmd: Cannot install package kmod-mtd-rw.
root@OpenWrt:~#
Result from SSH console when I try to install kmod-mtd-rw.
How can I install this package? or any other to do the same thing.
TIA