Hi,
First in your OSS1 tcode yous should maintain the local ip of SAP and not the public ip.
GWHOST=/H/66.21.71.120/S/3299/H/194.39.131.34/S/3299/H/oss001.wdf.sap-ag.de/S/3301,
In your case i can see you have maintained the 66.21.71.120 which is not correct.
Second inform your network team to check the firewal rule, your public ip should be able to communicate with SAP AG ip on port 3299.
Regards,
Anil Bhandary