@keneda @lakotaubp @phoenixlandpirat Thanks all of you.
I managed to update to 20.04 but I reinstalled the stable version because most application launchers got duplicated and Teleports didn't work.

@mrt10001 I have managed to add the account in Dekko using that off password you suggested. Thanks a lot.

@domubpkm
Mozilla/5.0 (Linux; Ubuntu 20.04 like Android 9) AppleWebKit/537.36 Chrome/87.0.4280.144 Mobile Safari/537.36

@kimo
I've been able to config proton vpn conexion on my Volla X with a fresh 20.04 focal.
I did the same as with 16.04, but without the vpn app and it works.
I can choose sha-512, but it works too choosing "by default"

@jarop Take a look to https://forums.ubports.com/post/32296
Files created from the OVPN must either be created on the terminal itself or transferred from the computer. But not sent, for example, by email, because they wouldn't work.
Good luck.

@jarop
I use protonvpn on focal.

It works

@Bolly Thanks a lot

@Chan1234 I am a newbie and know very little, but I managed to get my VPN up and running following this tutorial and with the help of other users.

https://ubports.com/de/blog/ubports-blogs-nachrichten-1/post/using-vpn-in-ubuntu-touch-3065

aquaris e4.5
Volla phone X

@ubuntumale I configured proton VPN without 'VPN editor' app, just with the option of VPN Configuration, in a Volla X Focal . It works.

@kimo
I've been able to config proton vpn conexion on my Volla X with a fresh 20.04 focal.
I did the same as with 16.04, but without the vpn app and it works.
I can choose sha-512, but it works too choosing "by default"

@domubpkm
Mozilla/5.0 (Linux; Ubuntu 20.04 like Android 9) AppleWebKit/537.36 Chrome/87.0.4280.144 Mobile Safari/537.36

@kristatos You are right, uNav works. I didn't have patience. It takes a long time to detect gps ...

After installing focal 20.04, I comment some changes:
.- the alarm allows you to choose tones, but always sounds 'Alarm clock' even if you have another one selected.
.- The VPN does not work with mobile data, although it does with wifi. I contacted my phone operator in case it was an APN failure, but apparently not (in fact, it works with that same SIM on an Android terminal and worked on my Volla X before the update.)
.- uNav app waits for gps indefinitely.
.-. Adjusts screen brightness automatically (previously it didn't).
Gracias a todos los que colaboráis. Great job.

@kristatos @domubpkm Thanks a lot!!
In the end I succeeded (I don´t know how, I would be unable to repeat it...) and I have a fresh install of focal 20.04 in my Volla X.