Server Move - Admin Login loads for 10 minutes and no mail

Hi all.

We've moved a large ZC from one hosting provider to another (new is a VPS).

Reconfigured, and front-end working great.

Initially, admin worked as normal too. But after around an hour, something changed - when logging in to admin, the page now loads for 10 or 15 minutes, before finally logging in. Once in, admin behaviour is normal. Nothing was changed in any files or the DB to cause this. Everything is exactly the same as it was when the admin was working as normal. Cookies/cache cleared.

Update check is DISABLED in both configuration and in /admin-dir/includes/local/skip_version_check.ini

Also, the site is not sending any mail to customers. Tried all mail settings to no avail. Another ZC on the same box (albeit 1.5) is sending using sendmail without issue. On the problematic one, /admin-dir/mail.php can't be accessed either - just doesn't load.

Any ideas?

Many thanks.

Update - after the admin login loading for 10 minutes, this time I got a 500 error. Refresh the page, and admin index.php appears and all works OK.

So strange!

Mail sorted - Setting 'Emails must send from known domain?' to Yes rectified it.

Aaaaand finally...admin has resolved itself too!

I wonder if this was something caused by DNS propagation? Or maybe something with mail is checked on login, so now that that's OK then login is OK?

RocketSites:

Or maybe something with mail is checked on login, so now that that's OK then login is OK?
There is no "mail" getting "checked" during login.

Login has no relationship to email in your old v1.3.8.
In v1.5.0+ an email is sent only when multiple password login attempts fail ... and you'll know about the failures because it will show an error message on-screen.

So, no, it has nothing to do with mail.

RocketSites:

We've moved a large ZC from one hosting provider to another (new is a VPS).

I don't wish to worry you, but......

RocketSites:

Reconfigured, and front-end working great.

Initially, admin worked as normal too. But after around an hour, something changed - when logging in to admin, the page now loads for 10 or 15 minutes, before finally logging in. Once in, admin behaviour is normal. Nothing was changed in any files or the DB to cause this. Everything is exactly the same as it was when the admin was working as normal.
<snip>
Any ideas?

...... This is a classic symptom of the server running out of memory and/or a software crash . How much memory does your new VPS have?

Cheers
Rod

RocketSites:

I wonder if this was something caused by DNS propagation?

It can't be ruled out. Time will tell.

If you simply changed the 'A' or 'NS' records in the DNS the updates usually only take a matter of minutes/hours.
If you performed a redelegation (changed registrars) it can take hours/days for the changes to propagate.

Cheers
Rod