Short answer: yes.
I have now tested without VPN, over Wi-Fi. That doesn’t change a thing, and I had some other odd experience as well. (“Test”/save of incoming server settings worked, seconds before and after a manual check didn’t fetch a test mail waiting at the server … More below.)
Trying to find pattern in something that’s intermittent, well …
Am I right in that K-9, not using push, but periodically checks, set at say 15m, always should do an initial check as soon as a data link is enabled, i.e. when Wi-Fi or mobile data is enabled?
Test without VPN:
No Wi-Fi enabled on mobile; sent test mail from computer; enabled Wi-Fi, no auto check as soon as enabled. Started K-9, and did a manual check. It downloaded the test mail. Fine, but not perfect.
(Disabled Wi-Fi and cleaned cache on K-9.)
Sent another test mail from computer; enabled Wi-Fi, no auto check as soon as enabled. Waited 20 minutes, no periodic check (it’s set to 15 min). Checked settings for incoming server, it worked (i.e. “Next” gave “settings saved” and returned to settings). Did a manual check, nothing… Did another “check” of settings for incoming server, and it worked, again.
Enabled debug log, and did another refresh/check, nothing. That’s really odd.
So far I’ve compared with the old mobile (computer is downloading, POP), but this time I logged into my e-mail via web mail, haven’t done for years, and there it is, my latest test e-mail.
During this time I could do as many manual checks with K-9 as I wanted on the new mobile, with Wi-Fi and no VPN, but no fetch…
Enabled Wi-Fi (with VPN) on the old mobile, and then went to K-9 and the test mail was already there, but no notification, probably because it was already marked as read (as I did that via webmail).
As mentioned I haven’t yet talked with the service provider; that said, isn’t it just wonderful, everyone can point in another direction.
The email service provider could say: well, since you have working email in your computer’s e-mail client (and have been working for 10-15 years), and your old mobile works with the app (apart from, as I mentioned above, some weird timing issue/other when at times some mail sent to an alias didn’t get fetched during manual checks) there’s nothing we can do, or indeed need to do. (It’s also possible that I do get to talk to someone that can, as mentioned, pull out some logs, or give other info, which can be of help, or help eliminate possible causes.)
In this forum, and I really appreciate all replies and help/information offered, it’s possible to not only point at the email service provider but also Android, perhaps the latest security update, the (new) mobile (model), my VPN service, my Wi-Fi connection (but the last two, and service provider are at least the same for both mobiles, one working and one not all the time, as it seems).
And in the wonderful world of mobiles, usually there is no way to uninstall and install an old version of an app (unless you have used some kind of backup, or download and sideload etc. That adds another obstacle. That said, the first few days it (the installed version) seemed to work; but since no major outbreak of problems, error is most likely somewhere else, but no help to find.
There are a couple of errors experienced here (I do understand that, as mentioned above, if a manual check doesn’t work there’s no need to try to “fix” periodic checks, fix the first one first.) However, it’s intermittent. As we know certain errors can have a couple of different causes, depending on situation, and that seems to be the case with: “java.net.SocketException: Connection reset”.
Before I give up and blame everything on the new Motorola and get on with life without a mobile email solution (that works), I guess I could start doing another series of test without the case for the mobile, if there is any material/something there that interferes with the Wi-Fi signal, which is ridiculous (a quick speed test I did at some point showed full speed and low ping). Or do tests only on mobile data (in fact I finished my test above with enabling VPN again, and did a test over mobile data instead of Wi-Fi, but K-9 didn’t fetch the test mail. (And yes, btw, some have had problems with notifications for other messaging apps on this model, but in my case we are talking about a direct manual check, done less than 3 m from a Wi-Fi access point.)
And I also don’t believe in randomly changing this or that, enabling/allowing everything just because. As mentioned all battery saving settings are disabled, for all apps. For example, in Settings, for each app, there are settings for mobile data and Wi-Fi; one of them, mobile data in background, is usually allowed for most (and is for K-9 since nothing is changed), but the next setting, unlimited data use, isn’t enabled, and there is no need for that, since that one only applies if Data limitation is enabled under Settings > network and internet, and it isn’t. There are no data limitations, so no need to enable unlimited for K-9. In fact, apart from perhaps some system apps, usually there are only a couple of apps that have unlimited data use enabled (if data limitations should become enabled at some point).
I gave up and downloaded the last test mail on my computer. As it is now, I would be happy if could just get manual checks to work, all the time (as I used the old mobile some months ago before changing to periodic checks).
What was the last thing I saw on the new mobile before I called it a day? Wifi or mobile data is now disabled. A spinning wheel in the notification area, can’t believe my eyes, and if I look at K-9’s app icon on the home screen there is a dot (we usually see this when there are new mails, or as in this case a failed check that takes extra long time)…
What are you doing K-9? There’s no data link to use.