Hello,
First, sorry for my poor English, I’m French.
I use AXT 1800 as a router with 2 entries, an ethernet for the router of my adsl provider and Wifi repeater for my new StarLink.
With my PC, connected to the AXT1800 by WiFi or by ethernet I can send emails with no issue, using Outlook or the email web page of my adsl provider.
With my iPhone Xs Max (iOS 16.6) and my iPad Mini 4 (iOS 15.7.8) I have access to Internet via AXT1800 Wifi and I receive all my emails. But I can’t send any email via the native mail application with the 2 smtp servers I use. They are on Port 465.
The issue is the same if I connect the router with WiFi 2.4 GHz or 5 Ghz
If I connect directely to Starlink or to my ADSL router, no issue to send emails.
Do I have something to configure in the AXT 1800 router ? If yes, I should appreciate a step by step explanation 
Thanks for your help.
Christian.