Help to get back in the road pls

All the time I didn't have any issues and played league from phone router as a modem. But now issue appearing every single time i enter the game. Swam deeply in the whole forum of Riot, but nobody gave me a decent solution for that. Please help me, as it's really frustrating. ** "There was an unexpected error with the login session. Please try again"**

I tried everything, changing DNS server, reinstalling the game, totally disable the firewall, all anti-viruses apps. As I already said, i have no issues playing from home broadband router, but ping is too high, especially when everyone home. I never had issues playing from a phone, honestly, don't know what's happened. Maybe after your recent update, maybe something else. I need a smart solution. You also can go in the community forum and have a look at how many people having the same issue!!