Obviously this was a huge issue for the Germans, so why wasn't it an issue for the Russians? They had used scorched earth tactics, and ripped up their infrastructure to slow the German advance, how were they able to sustain such vast supply lines where the Germans couldn't?
It is a mostake to think the Germans couldn't keep it up. However, the Soviets could do it better.
The Soviets had access to many more trucks and much more fuel. They were also surging with natural and imported resources, with Which they could rebuild. They had the benefit of pushing the war indefinitely westwards, and as they did, they were able to repair with a sense of permanence and security.
All these factors, but especially their overwhelming superiority in resources, gave them the noticeable edge over Germany in advancing back across Europe.
However, this is all relatively speaking. Even with these benefits, had been mauled of much civilian and military life. By the time the Reds reached Berlin, they were experiencing shortages in manpower. Their organization abilty and efficiency were badly wounded, and they would have been stalled going further west even in the face of the remaining weaponless German divisions.
That's why the Western Allies had to retreat in order to give the Red Army it's maximum allocated territory, for it failed to reach those areas by the time Germany surrendered.