I'm speaking from my understanding of the Free City of Danzig and its role in German-Polish relations during the interwar era (which I've done some substantial research on): Weimar, and later Nazi, Germany hated that both East Prussia and Danzig were separated from the rest of Germany. A lot of effort was made during the Paris Peace Conference to keep the territory contiguous, at one point even proposing that the Poles could simply have their access to the sea (which was part of Wilson's Fourteen Points) via a highway and/or railway. This was rebuffed by the Allies, who retorted that if such a proposal was good enough for the Poles to use, then the Germans could do the same in terms of accessing Konigsberg and the rest of East Prussia.

Keep in mind that in Danzig in 1919, some 96% of the population self-identified as being German, not Polish. Thus they also were not thrilled with being effectively cut off from the rest of Germany, both by being in a "Free City" and having to go through Poland. It is not surprising then that one of the early strongholds of Nazism was indeed in Danzig, with the 1931 elections giving them 12 of 72 seats in the city legislature (enough to sway the vote their way); they won a majority of seats in May, 1933, a few months after Hitler was appointed Chancellor in Germany.

I can't speak on how it effected East Prussia's working relationship with the rest of Germany, but this should give some idea that the very idea of Danzig being an independent city (and the Polish Corridor that went along with it), was an irritation to say the least to interwar Germany.