upload api dont allow upload of big files (error 500)

[CvH]

I try to upload a file to the proxmox (latest + all updates) storage with the api.
Small files (~16kb) actually work, bigger files create a error 500.
The file gets created at the /var/tmp folderand gets deleted after the error 500. It does not matter if I upload to a local storage or a remote one.

remote:

root@remote:~# curl 'https://10.10.10.10:8006/api2/json/nodes/pve1/storage/local/upload' -H 'Authorization: PVEAPIToken=uploader@pve!upload_template=...-...-...-...-...' -H 'Content-Type: multipart/form-data' -F "content=iso" -F "filename=@ubuntu-24.04.iso" -kv
*   Trying 10.10.10.10:8006...
* Connected to 10.10.10.10 (10.10.10.10) port 8006 (#0)
* ALPN: offers h2,http/1.1
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* TLSv1.3 (IN), TLS handshake, Server hello (2):
* TLSv1.3 (IN), TLS handshake, Encrypted Extensions (8):
* TLSv1.3 (IN), TLS handshake, Certificate (11):
* TLSv1.3 (IN), TLS handshake, CERT verify (15):
* TLSv1.3 (IN), TLS handshake, Finished (20):
* TLSv1.3 (OUT), TLS change cipher, Change cipher spec (1):
* TLSv1.3 (OUT), TLS handshake, Finished (20):
* SSL connection using TLSv1.3 / TLS_AES_256_GCM_SHA384
* ALPN: server did not agree on a protocol. Uses default.
* Server certificate:
*  subject: OU=PVE Cluster Node; O=Proxmox Virtual Environment; CN=pve1.blah.localdomain
*  start date: May 27 00:51:15 2024 GMT
*  expire date: May 27 00:51:15 2026 GMT
*  issuer: CN=Proxmox Virtual Environment; OU=...-...-...-...-...; O=PVE Cluster Manager CA
*  SSL certificate verify result: unable to get local issuer certificate (20), continuing anyway.
* using HTTP/1.x
> POST /api2/json/nodes/pve1/storage/local/upload HTTP/1.1
> Host: 10.10.10.10:8006
> User-Agent: curl/7.88.1
> Accept: */*
> Authorization: PVEAPIToken=uploader@pve!upload_template_01=...-...-...-...-...
> Content-Length: 144639246
> Content-Type: multipart/form-data; boundary=------------------------a5af44c3ccf486cd
> Expect: 100-continue
>
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
* old SSL session ID is stale, removing
* Done waiting for 100-continue

proxmox:

root@pve1:~# tail -f /var/log/pveproxy/access.log | grep -Ei storage
::ffff:10.10.10.11 - uploader@pve!upload_template_01 [22/07/2024:07:17:56 +0200] "POST /api2/json/nodes/pve1/storage/local/upload HTTP/1.1" 500

root@pve1:~# journalctl -u pveproxy.service -f
Jul 22 07:32:43 pve1 pveproxy[1210707]: problem with client ::ffff:10.10.10.11; Connection timed out

Any ideas what could be the problem ?