Irkutsk-Ulan Bator train booking by rw.by

Hello.
Has anyone booked Irkutsk to Ulan Bator train tickets using rw.by? On the rw.by website the button to make the booking does not appear. Am I making a mistake?
Any other inputs or tips on how to book train tickets from Irkutsk to Ulan Bator. I plan to travel in late September/ early October.
Thank you for your help.
Cheers

Hello! I’m traveling from Moscow to Irkutsk, arriving on September 11th. I wanted to continue by train to Ulaanbaatar, but I couldn’t buy tickets through tutu.ru due to various problems (there are only 1 or 2 services per week, availability is shown very close to the travel date, etc.), so we’ll end up flying that leg with IrAero.

I could not book it via rw.by so I had my friends in Russia book it for me on the RZD website. If you know anyone in Russia I recommend you do this as the russiantrains website grossly overcharged.

Rw.by was good for tickets between Russia and Belarus and domestic Russian trains.

Another option of you have a VPN with Russian virtual IPs like Proton, is to get set up with Pay In Russia and their 10% fee to get rubles will be less than the 30% that these agents charge. Then you can use those rubles to book ok RZD.