I already had that, but I changed it back now. So I'm getting "connection to storage server failed" instead
# tshark -ni enp1s0 -Y 'ip.addr == 192.168.0.15 or ipv6.addr == fd00::15'
Running as user "root" and group "root". This could be dangerous.
Capturing on 'enp1s0'
7 18.527784502 192.168.0.15 → 192.168.0.11 TCP 74 38560 → 993 [SYN] Seq=0 Win=64240 Len=0 MSS=1460 SACK_PERM=1 TSval=1995173067 TSecr=0 WS=128
8 18.527822019 192.168.0.11 → 192.168.0.15 TCP 74 993 → 38560 [SYN, ACK] Seq=0 Ack=1 Win=65160 Len=0 MSS=1460 SACK_PERM=1 TSval=1591404900 TSecr=1995173067 WS=128
9 18.527947837 192.168.0.15 → 192.168.0.11 TCP 66 38560 → 993 [ACK] Seq=1 Ack=1 Win=64256 Len=0 TSval=1995173067 TSecr=1591404900
10 18.528601748 192.168.0.15 → 192.168.0.11 TLSv1 583 Client Hello
11 18.528615136 192.168.0.11 → 192.168.0.15 TCP 66 993 → 38560 [ACK] Seq=1 Ack=518 Win=64768 Len=0 TSval=1591404901 TSecr=1995173068
12 18.541289100 192.168.0.11 → 192.168.0.15 TLSv1.3 1514 Server Hello, Change Cipher Spec, Application Data, Application Data
13 18.541313146 192.168.0.11 → 192.168.0.15 TLSv1.3 417 Application Data, Application Data
14 18.541471337 192.168.0.15 → 192.168.0.11 TCP 66 38560 → 993 [ACK] Seq=518 Ack=1800 Win=63232 Len=0 TSval=1995173080 TSecr=1591404914
15 18.542053860 192.168.0.15 → 192.168.0.11 TLSv1.3 146 Change Cipher Spec, Application Data
16 18.542064477 192.168.0.11 → 192.168.0.15 TCP 66 993 → 38560 [ACK] Seq=1800 Ack=598 Win=64768 Len=0 TSval=1591404914 TSecr=1995173081
17 18.542230024 192.168.0.15 → 192.168.0.11 TLSv1.3 90 Application Data
18 18.542236608 192.168.0.11 → 192.168.0.15 TCP 66 993 → 38560 [ACK] Seq=1800 Ack=622 Win=64768 Len=0 TSval=1591404914 TSecr=1995173081
19 18.542330787 192.168.0.15 → 192.168.0.11 TCP 66 38560 → 993 [FIN, ACK] Seq=622 Ack=1800 Win=64128 Len=0 TSval=1995173081 TSecr=1591404914
20 18.542361744 192.168.0.11 → 192.168.0.15 TLSv1.3 608 Application Data, Application Data
21 18.542411227 192.168.0.11 → 192.168.0.15 TLSv1.3 191 Application Data
22 18.542474883 192.168.0.15 → 192.168.0.11 TCP 54 38560 → 993 [RST] Seq=623 Win=0 Len=0
23 18.542490884 192.168.0.15 → 192.168.0.11 TCP 54 38560 → 993 [RST] Seq=623 Win=0 Len=0
in error.log
[22-Apr-2021 09:21:06 +0200]: <ftfndk25> IMAP Error: Login failed for user1 against mailserver.example.net from 192.168.20.118. Could not connect to ssl://mailserver.example.net:993: Unknown reason in /var/www/roundcube/program/lib/Roundcube/rcube_imap.php on line 200 (POST /?_task=login&_action=login)