Java: planksmp.net. Add it as a server, no port needed.
Bedrock: bedrock.planksmp.net, port 19132.
Type the Bedrock address exactly
19132 is the default Bedrock port, so a similar hostname on that port belongs to a completely different server. Get a character wrong and you will join somewhere else without any error telling you so. If the server does not look like PlankSMP, check the address before assuming the server is down.
Both editions share one world
Java and Bedrock players are on the same map, the same economy and the same auction house. There is no separate Bedrock world.
Still stuck? Open a ticket in the Discord.