Unable to verify username and password for AOL Mail

using iMac 2009 High Sierra. i have tried deleting and adding the accounts back in. have tried generate app password every day for a week, it works briefly then same issue. seems to be the outgoing server as i get emails but cannot send. if i go to the settings and select the server that is just like the one named on my macbook pro, it reverts to "none" in the dropdown menu.

works on macbook pro OS 12.5 but not on the older OS. AOL is no help. i have 2 AOL emails that i have used for 30 years. too much trouble to switch at this point.

thanks in advance for any advice