No internet connection in containers in Ubuntu 20.04

Hi folks!
I’m a newbie in this forum.
Sorry about my English level. Be patient with me!
This is my strange case:
After installing docker-ce with official docker web instructions, containers doesn’t see each other with default net connection bridge.
Deeping dive into network, bridge interface called docker0 has no route defined in “ip route” and containers are not linking to docker0.
If I launch docker run in two instances and test ping each other, they cannot see anything, and of course, cannot see internet.
Only works with network host (obviously)
I suspect that construction of docker0 bridge failed.
I am using Ubuntu 20.04 server in Strato (company name) hosting.
How can I create docker0 bridge manually or how can I repair this mess.
Thank you!