No connection from WebClients or mobile device anymore - IMAP failed to update folders

Hello,

After a simple reboot of our Windows Server 2019 the IceWarp suite does not accept any connections anymore from Web Clients neither our mobile devices.

WebClients can log in but they don't receive any mails nor cannot send. When trying to change a folder, we receive "IMAP failed to update folder".

Mobiles get a password request.

Here an extract from the log:

1.1.1.1 [1DA8] 13:39:29 1. IMAP connection failed: 127.0.0.1:143 / administrator@ourmail.com
1.1.1.1 [1DA8] 13:39:30 1. IMAP connection failed: 127.0.0.1:143 / administrator@ourmail.com
1.1.1.1 [1DA8] 13:39:31 ERROR administra administrator@pep-werbear get 2.38059
<?xml version="1.0" encoding="utf-8"?><iq uid="administrator@ourmail.com" sid="wm-5dcbe27895b58325100619" type="error"><error uid="imap_open"></error></iq>
1.1.1.1 [1DA8] 13:41:20 <<< administra administrator@pep-werbear webmail:iq:accounts set
<iq sid="wm-5dcbe27895b58325100619" uid="administrator@ourmail.com" type="set" format="json"><query xmlns="webmail:iq:accounts"><account action="refresh" uid="administrator@ourmail.com"/></query></iq>
1.1.1.1 [1DA8] 13:41:21 1. IMAP connection failed: 127.0.0.1:143 / administrator@ourmail.com
1.1.1.1 [1DA8] 13:41:23 1. IMAP connection failed: 127.0.0.1:143 / administrator@ourmail.com
1.1.1.1 [1DA8] 13:41:23 ERROR administra administrator@pep-werbear get 2.552586
<?xml version="1.0" encoding="utf-8"?><iq uid="administrator@ourmail.com" sid="wm-5dcbe27895b58325100619" type="error"><error uid="imap_open"></error></iq>
1.1.1.1 [1B90] 13:41:23 <<< 1462675047 administrator@pep-werbear webmail:iq:items get
<iq sid="wm-5dcbe27895b58325100619" type="get" format="json"><query xmlns="webmail:iq:items"><account uid="administrator@ourmail.com"><folder uid="__@@REMINDERS@@__"><item><values><ctz>60</ctz></values><filter><interval>2458800-2458802</interval></filter></item></folder></account></query></iq>
1.1.1.1 [1B90] 13:41:23 >>> 1462675047 administrator@pep-werbear webmail:iq:items get 0.100263
<?xml version="1.0" encoding="utf-8" ?><iq sid="wm-5dcbe27895b58325100619" teamchat_token="xoxp-552998c25cb0fd14d62ba10e0f49ddea2d51189625b2ef873660e4dc4d4ae14d" type="result"><query xmlns="webmail:iq:items"><account uid="administrator@ourmail.com"><folder uid="__@@REMINDERS@@__" count="0" recent="0" offset="0" rights="rl"></folder></account></query></iq>
1.1.1.1 [1B90] 13:42:12 <<< 4478566144 administrator@pep-werbear webmail:iq:items get
<iq sid="wm-5dcbe27895b58325100619" uid="4478566144373592001573648930655" type="get" format="json"><query xmlns="webmail:iq:items"><account uid="administrator@ourmail.com"><folder uid="Drafts"><item><values><subject> </subject><to> </to><sms> </sms><from> </from><date> </date><size> </size><flags> </flags><has_attachment> </has_attachment><color> </color><priority> </priority><smime_status> </smime_status><item_moved> </item_moved><tags> </tags><ctz>60</ctz></values><filter><limit>59</limit><offset>0</offset><sort><date>desc</date><item_id>desc</item_id></sort></filter></item></folder></account></query></iq>

Many thanks,
Ed

ps. I replaced the IP address and mail domain with placeholders...