in my other 3 S7, i had typed in "stratum+tcp://stratum.f2pool.com:3333" and it worked fine.
in the S7 (which is not working), with or without "stratum+tcp://", it CANNOT

be saved. Quite frustrating.
The issue is that the 'Save&Apply' does NOT work.
Perhaps a software upgrade might solve the issue but i've heard of cases where it becomes a brick after that....so its a scary step to take....
Really appreciate your thoughts and input...but still looking for the right solution.