@juhovh 

I have directed the antennas towards the tower but I'm not sure in which direction the actual 5G antennas are pointing. I will try your suggestion and when I visit the property next time. 
 

As an update on my side, I have updated the Deco (iPhone app) this morning and my internet is back. Let's see how long this lasts but I'm wondering if there was something wrong with the app and the remote connection as well? 
 

This is such a puzzle.. 

  @Lmsp87 

I spoke too soon.. the connection got lost and back to the red light issue.. 

  @Lmsp87 

Now - comes to my latest check list what to do in the specific location I have (in the middle of three base stations, and one of those giving weak 5G that actually provides less download speed than 4G+)

This is now based on the latest firmware 1.1.7:

This is how I do it with the latest FW (apologies for menu names may not be 1:1 as I am translating them from Finnish to English)

1) If I know 5G s weak or just to start all this process by at least securing good 4G -> Disable 5G ("Internet", "Network mode": 4G only).  Of course is this "stupid" as 5G is the reason to have this router. And as I have written before, if I am using the X50 in urban area in Helsinki/Finland, I can leave the mode 5G preferred, and the X50 can operate on 5G (white status LED) weeks without any issues. Of course if your SIM does not support 5G, you will be "stick to 4G only" I assume.

2) Now there is a new menu in 1.1.7 "Frequency". Go there and let the device scan the available frequencies. May take 30 seconds to scan them. Now starts "guessing", as typically operators does reveal their base station exact locations or "claim" they do not know the frequencies of the base stations. Start removing all external antennas and remember to disable the external antenna. Place the Deco at the front of the window.

3) Select one - and go up and scroll down "Signal strength" and write down what it is "how many green bars" and value of "SNR". At the same time, write down the frequency and "EARFCN" and "PCI" numbers. You can alternatively check the SN in the menu "Deco placement", but the issue in there is not EARFC and PIC number available.

4) Go back and select another frequency and repeat steps 2) and 3) for all frequencies

5) Now change the Deco to the other side of the building you are e.g. to the opposite side. The idea is to see if your X50 can operate better on the other window pointing to another direction to see better some of the base stations. Repeat steps 2) and 3) as needed.

6) Now you should have many alternatives to choose. Now look at your papers, which window and which frequency is giving the best signal strength (green bars or higher the number is SNR (in decibels).

7) Now check that you have an ethernet cable and you can access to the Deco via laptop locally, just in case you mess up the Deco with the following manual settings. In the worst case reset the Deco.

8) Enable now "Internet", "Frequency" being "Automatic".

9) Look at the numbers EARFCN and PCI are giving the best value, and now go to "Internet" and "Frequency locking" - swipe the 4G slide button on, and now you need to type in the EARFCS and PIC numbers that were associated with the best signal strength. Save the settings. And now you are, as far as I know  "locked in" to the best base station around you, but the X50 can negotiate the best way to communicate with the base station.

Now you should enjoy the best connection. You may try to uuse some network speed analyzed like Ookla or equivalent. 

The challenge is now, that if your cellular provider will significantly change their network - this "lock in based on EARFCN and PCI" may (probably) make your device loose connection to network and I do not know to configure your X50 as my app on the phone cannot via internet manage the X50... (?)

BUT now it's time to try a directional antenna if you have. Now you station is locked in to the "best base station" you may enable the external antenna and you may try to orient the antenna towards the base station (if you know where it is) or just with trial an and error so see if you can find the maximum but turning it around e.g. in steps of 30 degrees and to watch the SN value. The higher the value, the better is the signal. At this phace you can nicely use the menu "Deco placement" as it provides the numbers you need and nice refresh button. Now you can utilize the menu nicely, as we are locked in to the one and only base station with "EARFCN" and "PCI" settings.

If you are lucky, you can improve your signal e.g. by one bar or so. If you know in the end the direction, then you may try to move the antenna to outside and higher... but I'm not an expert anymore with these maneuvers. I just placed the "Poynting pizza box" 4G/5G antenna on the window inside towards the direction I know the base station is.

In the end, enable daily reboot in X50 - just in case...

Also keep in mind that:

1) If you change your network operator, you have to do all this again (and enable all back to automatic/without externa antenna before doing this)

2)  This gets more complicated if you have 5G. Due to my geolocation I have not been able to utilize reliably. 5G has also manual settings, there you select the channel, and I have not figured out how all this process should go if having 5G in the picture. And due to my limited knowledge, I do not know if EARFCN and PCI are related to 5G or for 4G only... if you know, I would be happy to hear.

  @HenrikEkman 

Now it would be nice if David-TP at TP-Link would review what I wrote - am I correct or not?

Hi!
Just wanted to comment here, if someone has a similar issue, and I seemed to find a solution that got my X50 5G working.
My problem was, that the X50 worked fine with Elisa and Telia ISPs, but with DNA it gave me red light and the internet connection stayed on for about couple of minutes and then dropped and started to show red light.
1. I changed the Carrier to be fixed to DNA (don't know if this helped)

2. I changed the Network Mode to "4G Only" as my hypothesis is, that Deco wanted so bad to have 5G that it "ignored" other connections. This seemed to fix my problem

3. FW: 1.1.4 (newest for me, Deco does not want to update it on 2.12.2024)

4. I rotated my double MIMO antennas according to App to have better connection (I think this was the number 2 reason to get it working)

  @Herkkutatti5000 while I'm currently abroad, my Deco is also in Finland and using the DNA network with an external MIMO antenna.

I got red light twice with v1.1.7 and have now updated to v1.2.0 firmware, will wait and see if the problem still appears. So far the internet connection has been cut off twice, but in both cases the modem recovered on its own and didn't need to unplug the device, so fingers crossed there's some improvement. DNA uses the 700MHz N28 band for its 5G in most areas in the country, with higher frequences in more densely populated areas that require higher bandwidth. The 700MHz band is supposed to have a very high penetration so it's unlikely 5G connection would drop before 4G, but I suspect the NSA mode of using both 4G and 5G bands simultaneously has been occasionally causing issues.

If you're stuck on v.1.1.4 firmware it's most likely because you have a v1.2 hardware X50-5G. The newly released v1.2.0 firmware is only released for the original v1.0 hardware, and they also seem to now have a v2.0 hardware that I have no idea what features would that include. I hope TP-Link will make some updates for the v1.2 hardware as well, because it's not nice to be stuck on an old firmware.

  @juhovh 

Moi Juhov  - kiitos vastauksestasi

Hu Juhov - thank you for your reply,

I appreciate your reply, as I'm also learning from it like:

* 5G can also be on frequencey as low as 700MHz - so actually there is some hope that 5G can penetrate thru forrest or "fly over the lake" like in my case. If I choose the operator right

Question: Have you by the way ever been found a map of the channels that Deco reports how do they relate actual frequencies in MHz or GHz?

Qestion: NSA - sorry to say, I do not know what it means, any change to drop a hyperlink to find out more about this?

Question: Am I right Juhov that your observation at the moment are based on v1.2.0 and you are not using frequency locking feature (so far)

Rgrds, Henrik