Hello,
I'm a new OpenWrt user, and the situation described here happened to me :
Unfortunately , after installing ver. 22.03.5 the WAN port did not work, and I thought of downgrading to an older version of OpenWrt.
Currently I have two versions of Open Wrt installed on two partitions, ( primary) ver. 22.03.5 and (secondary) 22.03.2, and I can't go back to the factory Linksys Firmwer.
What should I do in this situation in order to have the liksys stock firmware back on one ( primary) partition and Open Wrt on the other ( secondary), and not mess up the device ?
The link you provided gives outdated informations.
Since 22.03.3 you can flash anything (factory, sysupgrade, Linksys OEM - see link, bottom of the list). So in your case go to your current 22.03.5 and flash Linksys OEM. You will have several warning messages. Bypass.
FYI, I have both partitions running OpenWrt and no issue whatsoever (one 23.05.0rc2 and one snapshot).
I prefer to make sure before I mess something up, but if I understand correctly, you mean uploading this img file ( is that what you meant when you wrote Linksys OEM) from this link https://www.linksys.com/support-article?articleNum=293921 using from within OpenWrt - SYSTEM->Backup/Flash FIrmware -> Flash new firmware image ?
Correct me, but if I want to upload it to the primary partition, I should do it from within OpenWrt installed on the secondary partition ?
Yes. But there is no importance of having it installed on a partition or the other. Everything works fine wherever it is installed.
Warnings are normal : DON'T KEEP setting when flashing Linksys.
I think that your issue is simply because you are using an older OpenWrt. As long as you have 22.03.3 (or higher), you can flash anything where you want. You can even sysupgrade keeping settings. I'm flashing about once a week, using partition in alternance.
Good.
I would recommand to prepare your device to 23.05. Follow the tutorial in the doc. You can always use any Linksys or 22.03 if you like, but your device will be ready for 23.05.