Just in case, here are several alternative links if the main one doesn't work:
Main:
tg://proxy?server=proxy.digitalresistance.dog&port=443&secret=d41d8cd98f00b204e9800998ecf8427e
Iran:
tg://proxy?server=alternative-iran.proxy.digitalresistance.dog&port=443&secret=d41d8cd98f00b204e9800998ecf8427e
Russia:
tg://proxy?server=alternative-russia.proxy.digitalresistance.dog&port=443&secret=d41d8cd98f00b204e9800998ecf8427e

Feel free to share, but remember that the main one has the best infrastructure and provides optimal performance.