I tried multivalues in the list view page (allitems.aspx) and it works there: For example i can write something like :
?filtername=City&FilterMultiValue=*land* And it will filter the column "City" with values CONTAINING land anywhere in sentence. And it works there (on the allitems.aspx page).
To make the url filter on a basic page (where you can add webparts) you have to add the list and then you add to the url
So far i can easily set a filter but i can only do it with FilterValue,
FilterField1=City&FilterValue1=landAnd this will only find values that are the exact word "land". If i try the multivalue filter i can use on the allitems.aspx page, it won't work with the webpart. So far I don't know how to make it work there.
I use html form webpart and created a custom form that sets the url once you click on the search button. I use this method because with webpart connections you can only set filter on one single column.