After some trail and error I fixed the bug for my website. I will share it with the others maybe it can help anyone

My problem was that if you go to second page of a category or manufacturer and then change to another category/manufacturer you are not able to go the page 1. (you get stuck on page 2 and no possibility to reach page 1)
The solution for me was, that page 1 exist out of 2 url's but sh404SEF only uses 1. so I went to the "view/edit custom redirects" and changed the url's in 2 different names.
Page 1 (like in the module produced)
domain.com/index.php?option=com_virtuemart&Itemid=1&lang=nl&manufacturer_id=5&page=shop.browse
Page 1 (indicating the first page, bottom of VM)
domain.com/index.php?option=com_virtuemart&Itemid=8&category_id=&lang=nl&limit=30&limitstart=0&manufacturer_id=5&page=shop.browse
Both had the same SEF url in my system, domain.com/Manufacturername.html, I left the short url as it is and changed the second one because that is the one at the bottom of VM that directs to the wrong page.
You can name the second url anything you like and it will work.
I made it just like the others to keep the system clean, 'domain.com/manufacturername/Page-1-30.html'
so now you have the following urls:
domain.com/Manufacturername.html =
domain.com/index.php?option=com_virtuemart&Itemid=1&lang=nl&manufacturer_id=5&page=shop.browse
domain.com/manufacturername/Page-1-30.html =
domain.com/index.php?option=com_virtuemart&Itemid=8&category_id=&lang=nl&limit=30&limitstart=0&manufacturer_id=5&page=shop.browse
domain.com/manufacturername/Page-2-30.html =
domain.com/index.php?option=com_virtuemart&Itemid=8&category_id=&lang=nl&limit=30&limitstart=30&manufacturer_id=5&page=shop.browse
and so on! Hope this helps anyone, it at least did for me.