Goodday,
We received a new RB4011 with OS 7.8 pre-installed.
Routerboard factory firmware is also 7.8
So we are unable to downgrade the router to a long-term version what we normally do placing this equipment on customers sites.
Is there a way to downgrade?
Arjan
You normally can not go below factory version.
You could try using netinstall but I’m not sure that will work.
There is no long term on ROS7, so why bother ?
Today you are digging up all the old unanswered posts… 
You should be able to downgrade to whatever the “factory-software” is. If it is 7.8, there must be a new hardware revision that is not compatible with older versions.
If you need older versions, you will probably need to buy used, or find old stock (which is not likely, as all old stock was probably depleted during the last 2 years).
Maybe you can try a “new lamps for old” and trade with someone that has an old router but is running v7.8.
[demo@RB760iGS-1] > system/resource/print
uptime: 1h47m30s
version: 7.8 (stable)
build-time: Feb/24/2023 09:03:00
factory-software: 6.46.4
free-memory: 204.7MiB
total-memory: 256.0MiB
cpu: MIPS 1004Kc V2.15
cpu-count: 4
cpu-frequency: 880MHz
cpu-load: 1%
free-hdd-space: 3908.0KiB
total-hdd-space: 16.0MiB
write-sect-since-reboot: 718
write-sect-total: 990806
architecture-name: mmips
board-name: hEX S
platform: MikroTik
[demo@RB760iGS-1] > system/routerboard/print
routerboard: yes
board-name: hEX S
model: RB760iGS
serial-number: ************
firmware-type: mt7621L
factory-firmware: 6.46.4
current-firmware: 7.8
upgrade-firmware: 7.8
[demo@RB760iGS-1] >
Why, yes.
They deserve an answer too. No ?
And I stopped at April 1st 