Emails not being received

[#1]

I've been receiving emails via my iPhone without problems for a couple of years. Today, for the first time I suddenly got the error message IMAP plus net servers not responding but I haven't touched my iPhone settings. When I compare them with the settings shown on plus net there are no differences. Help! What can I do to fix it?

[#2]

I've been receiving emails via my iPhone without problems for a couple of years. Today, for the first time I suddenly got the error message IMAP plus net servers not responding but I haven't touched my iPhone settings. When I compare them with the settings shown on plus net there are no differences. Help! What can I do to fix it?

After much internet trawling, I think it might be down to the Advanced Settings but I can't see what these should be. Any ideas?

[#3]

Make sure that your iPhone isn't trying to force TLS/SSL and retest, hopefully that should sort it out for you.

[#4]

Thank you but the error message still keeps coming up. The advanced settings say: SSL-off, authentication-password, IMAP path prefix -/ and server port-143
Some internet suggestions have been to have the Path Prefix as INBOX but this makes no difference (unless something else needs to change?).
Thanks for your help

[#5]

What server address are you trying to connect to?
Are you able to log into the account using Webmail (preferably from a desktop).

[#6]

Yes no problem at all. The server address is imap.plus.net. If it isn't you'll have to tell me where to look 

[#7]

That's the correct server address, and the fact that you can use Webmail suggests that there's no problem accessing your account on the IMAP server. If SSL/TLS is disabled and you're using the correct login credentials then I'm at a bit of a loss.
Might be worth deleting/recreating the account on the iPhone.

[#8]

Thanks anyway. I was standing in a railway station when things went awry, so I blame Cross Country Rail entirely!
I'll do as you suggest.

[#9]

I hope you did not!!!  Issues such as this should be verified in different locations, as some mobile data cells can be deficient in their connectivity.