DNS stops itself randomly

The issue I am facing:
Hi All, I am quite new in Pi-hole but in last 2 week I had to reinstall it several times to try to fix an issue I am not able to fix. I can see my DSN is stopping on a ramp scale. when all it will start for the forst time it will be uo and running for 2 days more or less, then it will start stopping frequently. I fount this because the Admin console is not showing the web pace also if I reach it via IP.
I can access to RPI via SSH and when the interface show data I can see the DNS in red.
restarting it or, better, restarting the RPI solve for a while.
I have already tried to change power supply, cables and SD ( I have a RPI 2 with 2.0A power )

Details about my system:
RPI 2 SD 32GB Samsung Huawei power supply 2.0A

What I have changed since installing Pi-hole:
I tried several combination with no success...

Any Idea? In my "small" knowledge of Linux seems all ok, I have also tried to load Beta formware for RPI, no success.

Please post the token generated by

pihole -d

or do it through the Web interface:

Tools > Generate Debug Log

https://tricorder.pi-hole.net/et92ydn2v3

https://tricorder.pi-hole.net/z8f5zewmk7

Thank you

Also yesterday and this night. here the just extracted Token https://tricorder.pi-hole.net/0k28fdisuo
it is very strange
thank you