How to flash Tenda W268R?

Question

Network administration

There is such a router
Broadcom bcm5356c0kfbg -
Winbond W9864G6JH-6 processor - SDRAM
Winbond 25016bvs1g - Flash

google leads here https://wiki.openwrt.org/toh/tenda/w268r further here https://wiki.openwrt.org/toh/ tenda/w306r I download the firmware openwrt-15.05-ramips-rt305x-w306r-v20-squashfs-factory.bin I go to the router via the web, I select the file, I press the upgrade and they write to me "check upgrade file error" then the router is rebooted and everything remains the same. they write that you need to go to 192.168.1.1 but it doesn’t ping and it doesn’t go through telnet, SSH, ftp in general, I can’t flash it on the web in any way.
there are craftsmen who can tell about other types of firmware:

1.) Through the autoloader and the Ethernet port
To perform this option, namely to force the firmware to be uploaded, you can use the fact that most autoloaders contain built-in functionality for such purposes. Some contain a TFTP client, others a TFTP server, others an FTP client, and some even an FTP server. You need to find out:
the IP address of the autoloader (this is not necessarily the same IP address that the device has by default for access via the web interface!);
which of the above protocols are used;
whether the autoloader works as a client or as a server;
what port is used to connect to the default autoloader (If you can't answer this question, try the default port);
interface to which to connect;
you may need username and login (for access not to the web interface, but to the autoloader);
It's also important to know how long after power on your device accepts incoming connections to the autoloader. This can be, for example, a time of 2 seconds, starting from the 3rd second after turning on the device in the network.
Once you have answered all these questions, you can continue:
install, if necessary, the missing programs on your PC to access the router (so if the autoloader contains an FTP server, you need an FTP client);
read the instructions for using these programs! for example man tftp, man tftpd, man ftp, man ncftp, man ftpd, man pure-ftpd, or other documentation;
set a static IP address for your PC within the same subnet as your router's autoloader;
connect your PC to the appropriate port;
turn on your router;
establish a connection with the router exactly at the moment when the autoloader allows it;
follow the appropriate procedures for uploading the OpenWrt file to your router;
Do not change or reinstall the autoloader unless specifically stated to do so!
Note: Sometimes even the autoloader does not allow writing the firmware file to the flash memory of the device, for example, in Inventel DV4210 (AKA Livebox).
2. via autoloader and Serial port
→ generic.flashing.serial
3. via JTAG
→ port.jtag

Now I'm thinking how to find the UART here?

Answer 1

And why did you decide that the firmware from Tenda W306R will fit Tenda W268R?
Say thank you that the protection works, otherwise you would have already studied the JTAG manuals.
The board layout (PCB) is similar to Tenda W306R V2.0. This does not mean anything at all about firmware compatibility.
System-On-Chip : RT3350F - RT3052
!!!!! Flash: 2MB - 4 MiB
And most importantly:

Some devices w/ labeled FCC IDs of V7T268R may not actually use this board - one labeled as such was RT3050 based (the board was labeled as being for the W311R) w/ 2 MB Flash and 16 MB RAM
Based on the FCC filing date of this device, earlier model units may use BCM5356B0 rather than C0..

Answer 2

Of the interesting that absolutely the same architecture has 3q rn24f. That's just how I think it can be reflashed