I have home laptop on 3G - client
I have sisters laptop on Wi-Fi router - target
I have dedicated server - middle

All on Ubuntu

I created tunnel from target to middle

Code:
ssh -R 7778:localhost:22 middleuser@middleIP
Then I connect to middle from client

Code:
ssh middleuser@middleIP
And from it to target

Code:
ssh targetuser@localhost -p 7778
But here I receive this errror: Permission denied, please try again.

I actually already have success connections today, but then I broke smth...

Please help where to look first?

TIA