Upload to aws s3 fails

Dear all,
new to the forum, new to using AWS cloud, and sorry for a very basic question. Got a basic plan on aws, an instance EC2 with 300gb storage on s3, installed an linux 2 AMI, installed java, conda, nextflow, can run the ‘nextflow run nf-core/sarek -r 3.2.3 -profile test,docker --outdir results’ no issues. No I am trying to upload my sample-fastQ files into s3. Upload speed is miserable 1-5MiB/s, upload crashes, when using the AWS CLI or the s3 dashboard in a browser. Tried the s3-accelerate option, moved s3 to closest location (Frankfurt), tried multipart upload with 64MB chunksize already. Local internet connection is at 40-50MiB/s, LAN no wifi. Help appreciated - Kai