@haze10 

Hi,

many (if not most) of TP-Link's routers don't allow downgrade of the firmware via the router's configuration GUI.

The "device's current hardware version" error message is misleading in this case, but perhaps that is just a generic message that TP-Link implemented. 

So, if you want to go from the currently installed version 1.4.0 to version 1.3.0 and get an error, then you will probably have to do it another way.

@woozle 

Yes my mistake I had not seen that I was already at the latest version available.
But now after turning it off I have another problem.
It practically no longer connects to any 4g network.
I have already tried to reset and restart the device.
Also if I go to the section
network mode and select "only 4g" I get this error "Error code: 1
Internal error "
In practice it is now impossible for me to connect to 4g.
I also have the same operator on my smartphone and I have no problems connecting in 4g, even using a pocket wi-fi there are no problems.
How is it possible that now it no longer connects to the 4g network?

@haze10 

It's hard to tell what has gone bad.

Can you pull the SIM card from the MR600 and insert it into a smartphone to crosscheck that it is still working?

If the SIM card is still okay, then try to do a manual Network Search (Advanced > Network > Internet) on the router and see if it can find any mobile networks that are within reach.

@woozle the sim card works on other slides, trying to select the network I can select that of my operator but in any case nothing changes.  how is it possible that after switching off, it no longer takes 4G?

@haze10 I have the exact same problem. Did you find a solution?

I just got the router today. I put in my SIM card, powered on and it connected to 4G+. Everything was going great until I went into the settings and manually picked band 2. Some point shortly after that the router got stuck on 3G. I've tried changing the network settings back to '4G preferred' and 'Band: Auto' but no luck.

If I change network mode to 4G only I get this message

Error code: 1
Internal error

If I manually try to select a band now I get this message

Error code: 89534
No available band

It seems like changing the band has absolutely ruined the 4G connectivity with no way to get it back.

I also tried manual network search, resetting the router to factory settings, removed the SIM card and reinserted it. Created a new profile. Nothing is working, just stuck on 3G.

I actually had a Huawei CPE Pro 2 previously and switched to the MR600 v2 because I had some minor issues with it and just wanted a simple 4G+ router since I have no 5G signal. I was getting 4G+ all the time with the CPE Pro 2 so I know that my signal is strong. This is a much worse experience and a really bad experience with my first tp-link product...

@niallobr 

Check out this thread https://community.tp-link.com/en/home/forum/topic/505072 or perhaps send a private message to the user "TP-Link" directly.

@TP-Link hello, do you have more information about a release date for the 1.5.0 fix please ? I can no longer work because of this bug, although I installed the box two weeks ago. 

@TP-Link 

Hi. Is there any news on the 1.5 update to fix this issue?, I purchase and installed my MR600 V2 yesterday and initially worked well, but as with others, following a reboot i am unable to connect to 4g, cant change bands or network mode.

Regards