Issues in S3 Buckets in Ireland Region - missing TSval & TSecr on 3 way handshake

Hello everyone, We are experiencing issues with some S3 Buckets in the Ireland Region. Sometimes in the 3-way handshake, the TSval & TSecr on the [SYN ACK] are not returned (RFC 1323). When this happens we see a huge drop in the bandwidth. In other cases, it works fine. We are trying to download files from Italy with a latency of 40ms. The drop in performance might be caused by the CCR2004 Mikrotik router that is delaying the ACKs that are discarded by the S3 bucket, thus leading to a reduction in the congestion window.

Why some S3 buckets are not returning the TSval & TSecr? (we have found that at least the subnet 52.218.0.0/16 is affected by this behaviour) Anyone else has the same problem with this latency (40ms)?