During the siege of Leningrad, the Soviets built an ice road over Lake Ladoga called the Road of Life to supply Leningrad during the winter months.
What prevented the Axis (the Finns and a few German units) from building a similar road from Finland over the northern part of the lake from which to attack/disrupt/interdict this supply route? I'm "mirroring" the axiom that the best way to fight an attempt at "undermining" was to "countermine." Your mine intercepts their mine and you head it off before it is complete. Also, given the experience of the Winter War, perhaps the most threatening attack was that of Finnish snipers, on skis.
Was it physically infeasible to do so? Or was it physically feasible, but it didn't fit it in with the Finns' overall military and political strategy?