The current UN sponsored peace talks have been delayed until February 25 th largely because Russia has been lying about why it is really in Syria and that lie is both obvious and a major factor in preventing the peace talks from starting. The problem is that Russia is concentrating most of its considerable firepower on rebel groups that are hurting the Syrian Assad government forces the most. By American count only about ten percent of Russian air strikes have been against ISIL (Islamic State in Iraq and the Levant) and those targets were usually hit to protect Assad forces ... Not surprisingly these rebels refuse to participate in peace talks as long as the UN allows Russia to get away with their lies. In the last week this Russian support has enabled Assad forces to cut rebels in Aleppo off from Turkey (a primary source if reinforcements and supplies). This is a major defeat for the rebels.
UN officials believe they can work out the disputes between the rebels and the Russians in time to get the peace talks going by the end of the month but that remains to be seen because the Syrian rebels blame Russia for most of the current government success. As a result the rebels contribute to the failure of the UN peace talks by demanding a lot of pre-conditions aimed at the Russians. At the very least the rebels wanted the Russians to halt their Assad support while peace talks go on. The rebels are asking for other concessions, like release of captured leaders lifting of sieges of some pro-rebel civilian areas. Russia refuses to comply with these demands.
Another issue the rebels are angry about was the UN agreeing to keep the Syrian Kurds out of the peace talks. This was something Turkey insisted on. There were other problems, like the tensions between Russia, Saudi Arabia and Iran which have also helped cripple UN efforts to get Syria peace talks going. The growing tensions between Saudi Arabia and Iran has made cooperation over brokering a Syria peace deal less likely. Russian efforts to mediate are also compromised because of tensions with Iran and the Saudis. Russia has backed away from earlier suggestions that they would support forcing the Assads out of the government (while allowing Assad allies to carry on instead) and offering the Assads refuge in Russia.
So far Russian bombers and attack helicopters have killed over 3,000 people. Russia claims that about a third of these dead have been ISIL with the rest being other rebels and civilians. These Russian air attacks are now frequently hitting over a hundred targets a day. Western critics accuse Russia of ignoring civilian losses. That is true but because of that the Russian air attacks have been more effective and have been of great assistance to the Western war against ISIL. Russia calls Western criticism hypocrisy especially since Western and Arab leaders backing the fight against ISIL are not pressuring Russia to change its ROE (Rules of Engagement) over this because everyone admits that this would just encourage ISIL to use civilians as human shields even more.
There's much more at the link.
It's a long report with a lot of detail, but well worth reading in full. In particular, I recommend its analysis of the actions and reactions of other players in Syria - Iran, Israel, Turkey and the Kurdish groups in Iraq, Syria and Turkey. The Syrian conflict is a tangled web of alliances, interests and chain reactions, and its complexity means there won't be any quick solution.
As a matter of fact, looking at the complexity of the situation there, one wonders whether Russia isn't being drawn into a similar situation to what the USA faced in South Vietnam. Over the past decade of the latter conflict, it was obvious that the South Vietnamese government only retained power and control because the USA backed it. When that backing was withdrawn, collapse soon followed - and the USA was humiliated in the eyes of the world for a generation or more. Will the same fate befall Russia in Syria? It's a good question. Students of history will doubtless already have noted the parallels.