TCP Server Socket with keep alive / No Timeout INT occurs when client is killed

i am using a WIZ550IO for communication.
E.g. SOCKET 7 configured as TCP Server, Keep Alive Timer set to 0x06 (30Sec) (see Dump Data below), Port 6000.
I connect a client, pull off the network connector, wait a minute so that the client has no chance to disconnect, and reconnect the network cable.
The socket remains now in the connected state 0x17.
I was of the opinion that now the WIZ module should determin the missing client by sending a keep alive packet and set the timeout INT (my application would initialize the socket after this)
But is does not. As well when i set socket CMD 0x22 to send the KA packet i can see no activity (Whire shark)
The only way is to transmit at least one byte, then the WIZ module start the retrys and sets timeout after the period set.
See the register setting of the module common and socket common below.
Anything missing or wrong ?
Thx in advance for helpful input.

Module common settings
Addr. Value Descr.
0x0000 0x00 MODE
0x0001 0x0A Gateway ADR0
0x0002 0x00 Gateway ADR1
0x0003 0x00 Gateway ADR2
0x0004 0x8A Gateway ADR3
0x0005 0xFF Subnet 0
0x0006 0xFF Subnet 1
0x0007 0xFF Subnet 2
0x0008 0x00 Subnet 3
0x0009 0x00 MAC 0
0x000A 0x08 MAC 1
0x000B 0xDC MAC 2
0x000C 0x54 MAC 3
0x000D 0x35 MAC 4
0x000E 0x40 MAC 5
0x000F 0x0A IPADR 0
0x0010 0x00 IPADR 1
0x0011 0x00 IPADR 2
0x0012 0x32 IPADR 3
0x0013 0xF0 INT TMR0
0x0014 0xF0 INT TMR1
0x0015 0x00 INTERRUPT
0x0016 0x00 INTMASK
0x0019 0xF0 RETRYTIME0
0x001A 0xF0 RETRYTIME1
0x001B 0x08 RETRY COUNT
0x001D 0x00 LCP MAGIC NR
0x001E 0x00 PPP DEST MAC 0
0x001F 0x00 PPP DEST MAC1
0x0020 0x00 PPP DEST MAC2
0x0021 0x00 PPP DEST MAC3
0x0022 0x00 PPP DEST MAC 4
0x0023 0x00 PPP DEST MAC 5
0x0024 0x00 PPP Session ID0
0x0025 0x00 PPP Session ID1
0x0026 0xFF PPP Max SEGSize 0
0x0027 0xFF PPP Max SEGSize 1
0x0028 0x00 UnreachIP0
0x0029 0x00 UnreachIP1
0x002A 0x00 UnreachIP2
0x002B 0x00 UnreachIP3
0x002C 0x00 UnreachPORT0
0x002D 0x00 UnreachPORT1
0x002E 0xBF PHY Config
0x002F 0x00
0x0030 0x00
0x0031 0x00
0x0032 0x00
0x0033 0x00
0x0034 0x00
0x0035 0x00
0x0036 0x00
0x0037 0x78
0x0038 0x25
0x0039 0x04 Version NR

Socket base settings
Addr. Value Descr.
0x0000 0x21 MODE
0x0001 0x00 SOCKET COMMAND
0x0003 0x17 SOCKET STATUS
0x0004 0x17 PORT 0
0x0005 0x70 PORT 1
0x0006 0x70 DEST MAC 0
0x0007 0x4D DEST MAC 1
0x0008 0x7B DEST MAC 2
0x0009 0x87 DEST MAC 3
0x000A 0x6F DEST MAC 4
0x000B 0x88 DEST MAC 5
0x000C 0x0A DEST IP ADR 0
0x000D 0x00 DEST IP ADR 1
0x000E 0x00 DEST IP ADR 2
0x000F 0x04 DEST IP ADR 3
0x0010 0xCC TCPserver PORT 0
0x0011 0xE9 TCPserver PORT 1
0x0012 0x05 MAX SEG Size 0
0x0013 0xB4 MAX SEG Size 1
0x0014 0x00
0x0015 0x00 SOCKET IP TOS
0x0016 0x80 SOCKET IP TTL
0x0017 0x00
0x0018 0x00
0x0019 0x00
0x001A 0x00
0x001B 0x00
0x001C 0x00
0x001D 0x00
0x001E 0x02 RX BUFF Size
0x001F 0x02 TX BUFF Size
0x0020 0x08 TX free Size 0
0x0021 0x00 TX free Size 1
0x0022 0x69 TX read PTR 0
0x0023 0x12 TX read PTR 1
0x0024 0x69 TX write PTR 0
0x0025 0x12 TX write PTR 1
0x0026 0x00 Received Size 0
0x0027 0x00 Received Size1
0x0028 0x00 RX Read Pointer 0
0x0029 0x42 RX Read Pointer 1
0x002A 0x00 RX Write Pointer 0
0x002B 0x42 RX Write Pointer 1
0x002C 0x1F Interrupt MASK
0x002D 0x00 Fragment Offset IP Header 0
0x002E 0x00 Fragment Offset IP Header 1
0x002F 0x06 Keep Alive Timer
0x0030 0x01

No, everything is correct.

Server waits for incoming packets, and it will be waiting forever until it will receive something - FIN, RST, or data.

You do it manually (0x22), or use keep-alive timer.

Datasheet says:

KA packet is transmittable after Sn_SR is changed to SOCK_ESTABLISHED and after the data is transmitted or received to/from a peer at least once.

There will be no keep-alive (neither 0x22 nor automatic using timer) if there was no prior communication.

Thank you for the information.
In fact the TCP server starts sending KEEP ALIVE packets first when a TX packet was transferred by the TCP Server.
RX packets witout response by the server will not start the KA process. (even if KA timer is set or CMD 0x22 is written to the Command Reg.)

I will resolve the detection of those dead connections in an other way. (no activity, after a defined timeout , send 1 Byte TX, this should start the KA process)