I tried the elgg block and finally it worked on our server, but only on the internal network! In the lms-host I used internal addresses (192.168...) and in Moodle block_eportfolio_baseurl I tried also the internal address and it worked, but this is the address moodle uses to make the link to elgg. From outside (internet) the internal link didn't work (of course), but when I fill in the external URL in block_eportfolio_baseurl, a course in Moodle where I put the portfolioblock reacts very(!) slow and it shows the "join me"-button over and over again.
So, block_eportfolio_baseurl with the internal address is ok, but with the outside URL the portfolio-block seems not to get contact with elgg.
I put moodle in /html/moodle on our server and elgg in /html/elgg. Does someone have an idea?