Can receive, but not send Spectrum email away from home on iphone/laptop

Hello, I notice this question has been asked before, but I haven't seen a solution yet. Hoping someone can help. I have a Spectrum/roadrunner email. I receive email when away from home on my iPhone, but absolutely cannot send email no matter what configuration I try. Same for my Apple laptop. Away from home I can receive, but cannot send email. Works fine at home on both devices. I've tried every suggestion I find online and nothing works. Calling Spectrum is a joke - they have no clue. Thank you.