I would like to book a train ticket from www.vr.fi, but I keep seeing the status message, "Usage is temporarily restricted from outside Finland." Does anyone know why this restriction is in place, or if/when it's likely to be lifted? Are there other ways I can purchase a ticket for this route in advance?

If I'm not able to purchase a train ticket in advance, can I rely on being able to buy one at the station on day of travel, or do the trains often sell out? I'm trying to travel from Turku to Helsinki on the morning of August 9, if that matters, and I don't arrive in Finland until the morning of August 8.