ELS61-E: can't HTTP POST more than 21584 bytes with AT^SISW | Telit Cinterion IoT Developer Community

Hello,

i am stuck with a problem posting a bigger dataset to a HTTP POST endpoint.

My problem is: i can't post more than 21584 bytes with repeated AT^SISW commands. Whenever i try more i get the following response from the module:

^SISW: 0,2
^SIS: 0,0,2200,"HTTP POST: https://els61.requestcatcher.com"
^SIS: 0,0,8002,"HttpHTTP POST: IllegalArgumentException Socket-Error:-1000"

My ATI1 is:

Cinterion
ELS61-E
REVISION 01.000
A-REVISION 00.026.00

Anyone knows what might be wrong?

Kind regards
mbank