Is your feature request related to a problem? Please describe.
The mqtt outdated error is very common (see https://github.com/evcc-io/evcc/issues?q=is%3Aissue%20outdated and https://github.com/evcc-io/evcc/discussions?discussions_q=outdated)

I think a better error message and maybe a other default value could help users.

Describe the solution you'd like
Show a error message outdated: try to increase the timeout. Maybe with a link to a docs page that gives more infos.
Maybe also have a reasonable timeout (30s?) to prevent the user to see this error completely.

Describe alternatives you've considered
Help user to add a timeout in their config.

Additional context
na