Something weird with Plusnet routing this morning

[#1]

Not sure this is the right section, but it seemed best...

My PC this morning wouldn't connect to my (hosted elsewhere) mail server, but would to several other mail services such as Gmail. Everything else seemed normal. Similarly my phone, which is on WIFI to my PlusNet hub 2 had the same symptoms.

Oddly accessing the mail system via its webmail interface (from my PC) worked fine, it was the IMAP/SMTP that didn't. So I knew the server is working (at least somewhat). 

Switching the phone to 4G it worked fine, so my first thought was DNS. Changed the PC to Google DNS and the problem was unchanged. 🤔

Switched the PC to my phone on 4G as a hotspot and it all started working.

Smells like a routing problem of some sort in PNs network, thoughts anyone?

[#2]

And weirdly, after about an hour or so of "downtime" it automagically started working again! 🤔

[#3]

Was that by any chance Outlook.com servers?

Intermittently I get firm connection failures to my outlook account using Outlook on the laptop and iOS Mail on the iPhone.  The latter just keeps requesting the password, to which I press CANCEL - sometimes it then just connects other times it will not connect for hours.

Similarly the laptop reports no connection but does not ask for the password.

[#4]

Hi @Townman no, not outlook.com, a personal domain hosted at a company called M247 who are quite large nowadays.

My email client(s) (Outlook on Windows and Apple email on IOS) just said server not found which is why I first suspected DNS.

As I explained above it wasn't that simple....... and similar oddities have happened before.

Also, not noted earlier, I have several domains hosted there and some other email accounts were working fine! It just happened to be my main one that was unavailable so I noticed first thing today.

[#5]

I had 'heavily pregnant pauses' sending email via a (FTTP) PN connection to an external e-mail provider (mythic-beasts) earlier today. The mails eventually got sent. At the speed of dial-up (or slower, actually).

Outlook.com and gmail not part of the above mix.

[#6]

So this is happening again this morning. Email working via PlusNet broadband up to some time after 9pm but is now not connecting for a specific hosted domain. It's fine via 4G on an iPhone! 😫 Something must be wrong with routing of email traffic somewhere related to PN surely, but what?

Note: It also works fine on my PC when I connect using my phone as a hotspot.

[#7]

@HPsauce 

Does the issue relate to (just) the M247 service again?

The fact that it works fine over 4G could point to a network pairing (routing) issue.  PATHPING to smtp.m247.com dies somewhere beyond the BT core peering network.  Might be worth raising a support issue with M247.  We have seen similar around here with some domains not having a network routing directive.

pathping smtp.m247.com

Tracing route to smtp.m247.com [89.238.137.123]
over a maximum of 30 hops:
  1  192.168.1.254
  2  195.166.130.249
  3  gi2-23-442.ptn-gw02.plus.net [84.93.253.75]
  4  core1-BE1.colindale.ukcore.bt.net [195.99.125.132]
  5  peer7-et-0-0-1.telehouse.ukcore.bt.net [62.172.103.158]
  6  109.159.253.91
  7     *        *        *
Computing statistics for 150 seconds...
            Source to Here   This Node/Link
Hop  RTT    Lost/Sent = Pct  Lost/Sent = Pct  Address
  1    1ms     0/ 100 =  0%     0/ 100 =  0%  192.168.1.254
                                0/ 100 =  0%   |
  2  ---     100/ 100 =100%   100/ 100 =100%  195.166.130.249
                                0/ 100 =  0%   |
  3   13ms     0/ 100 =  0%     0/ 100 =  0%  gi2-23-442.ptn-gw02.plus.net [84.93.253.75]
                                0/ 100 =  0%   |
  4   14ms     0/ 100 =  0%     0/ 100 =  0%  core1-BE1.colindale.ukcore.bt.net [195.99.125.132]
                                0/ 100 =  0%   |
  5   15ms     0/ 100 =  0%     0/ 100 =  0%  peer7-et-0-0-1.telehouse.ukcore.bt.net [62.172.103.158]
                                0/ 100 =  0%   |
  6   14ms     0/ 100 =  0%     0/ 100 =  0%  109.159.253.91

Trace complete.

[#8]

Thanks @Townman I'll look at that next time, it's already reverted to working fine though! 🤔

But yes it's only IMAP/SMTP on a specific hosted domain at M247, I have several and the others are working normally.

Also access via Webmail works perfectly so the actual mail server is up and running, the message I get is along the lines of server not found, rather than not responding or other timeout type errors which suggests it's a routing issue but I guess it could be a strange server-side issue. That's from both Outlook on W11 and Mail on IOS.