Problems connecting to WMS

Hi,

with every device (3040, 5070) that I upgrade to ThinOS 9.x (tried 9.1, 9.1.6, 2205) I can´t connect to my WMS server any more when connected through SD-WAN. The server is in a different domain, every time I try to access it, I get the following error log in wlogd.log:

[2022-08-16 10:36:20.873] N/WDAProc/WMS (1/1) wms: failed to validate. write EPROTO 34496511232:error:0D0680A8:asn1 encoding routines:ASN1_CHECK_TLEN:wrong tag:tasn_dec.c:1220:
34496511232:error:0D07803A:asn1 encoding routines:ASN1_ITEM_EX_D2I:nested asn1 error:tasn_dec.c:386:Type=X509_PUBKEY
34496511232:error:0D08303A:asn1 encoding routines:ASN1_TEMPLATE_NOEXP_D2I:nested asn1 error:tasn_dec.c:720:Field=key, Type=X509_CINF
34496511232:error:0D08303A:asn1 encoding routines:ASN1_TEMPLATE_NOEXP_D2I:nested asn1 error:tasn_dec.c:720:Field=cert_info, Type=X509
34496511232:error:1409000D:SSL routines:ssl3_get_server_certificate:ASN1 lib:s3_clnt.c:1242:
[2022-08-16 10:36:27.984] N/WDAProc/WMS (1/1) wms: failed to validate. write EPROTO 34496511232:error:0D0680A8:asn1 encoding routines:ASN1_CHECK_TLEN:wrong tag:tasn_dec.c:1220:
34496511232:error:0D07803A:asn1 encoding routines:ASN1_ITEM_EX_D2I:nested asn1 error:tasn_dec.c:386:Type=X509_PUBKEY
34496511232:error:0D08303A:asn1 encoding routines:ASN1_TEMPLATE_NOEXP_D2I:nested asn1 error:tasn_dec.c:720:Field=key, Type=X509_CINF
34496511232:error:0D08303A:asn1 encoding routines:ASN1_TEMPLATE_NOEXP_D2I:nested asn1 error:tasn_dec.c:720:Field=cert_info, Type=X509
34496511232:error:1409000D:SSL routines:ssl3_get_server_certificate:ASN1 lib:s3_clnt.c:1242:

I can ping the server without problems.

The Tomcat log on the WMS server just says "error 400".

WMS is a Windows Server 2016. It´s a bit of a different issue because this only happens on networks that are connected over SD-WAN. Our firewall admin checked that already and there are no blocks.

When I downgrade the devices to 8.6, everything works fine (same IP settings, same certs,..)

Thanks in advance!