Over the last few weeks, I have experienced issues with accessing IMAP mail through fixed cable broadband.
The issue seems to be intermittent. Now and again the IMAP server connects (I haven't checked but wonder if the connection comes about through a wifi drop out thus reverting to 4G/Hotspot)
Using Windows 10, Netgear CG3000v2 cable router, outlook 2016.
iPhone and iPad with mail client IOS 11.1 (multiple devices)
Ports are incoming 993 using SSL and SMTP port 465 using SSL, which is the recommended settings from my provider.
Until a couple of weeks ago there was no issue, everything worked fine. A couple of weeks ago I did start to experience dropouts and noticeably the email client stopped connecting to the server. Optus sent a technician and the internet problem seems to have gone away - the email issue is still ongoing.
The issue seems to be isolated to the broadband fixed connection - switch to 4G on mobile and issue goes away, hotspot desk device and again no issue.
I have not changed any settings on my router - so the question is has Optus started to block ports in the last few weeks?
Disappointingly, I have contacted support through chat, the first chat agent suggested borrowing a router to check if it is a problem with the router (it is 2 years old), before the connection dropped out so I had to start again with the second who told me it isn't an Optus issue as it is a 3rd party IMAP server. Before I could respond I was cut off and directed to a survey (wrong move!!!) Well it does actually only occur on the Optus network so I think it must be an Optus problem