Cannot sign in to aws console

I’m having problems getting to the signin page of aws in Ubuntu 20.04 with latest updates. As I suspect this to be a network problem, I’ve tried accessing with curl and openssl. Sometimes (randomly) following commands doesn’t fail and I get successful responses, but most of the time I’m getting following responses:

~ curl -vvv https://signin.aws.amazon.com
*   Trying 176.32.98.146:443...
* TCP_NODELAY set
* Connected to signin.aws.amazon.com (176.32.98.146) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* successfully set certificate verify locations:
*   CAfile: /etc/ssl/certs/ca-certificates.crt
  CApath: /etc/ssl/certs
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to signin.aws.amazon.com:443 
* Closing connection 0
curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to signin.aws.amazon.com:443

openssl s_client -connect signin.aws.amazon.com:443 
CONNECTED(00000003)
write:errno=0
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 0 bytes and written 313 bytes
Verification: OK
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
Early data was not sent
Verify return code: 0 (ok)
---

Some observations:

• signing.aws.amazon.com resolves to different ip addresses and I’ve checked I’m getting both successful and error responses from same ip addresses.
• When I get a successful response, usually next few calls are also successful if I keep trying.
• If I connect to a VPN, these calls never fail
• I have two ubuntu machines at home both of the have the same problem. I’ve installed curl to a windows machine and it never had the problem.
• Successful sessions are using TLSv1.2 as expected
• I have a very stable 100 Mbit connection with very low ping times and this problem doesn’t happen with any other domain
• Both commands fail after 23 seconds. However when they’re successful, it takes ~400ms.
• I tried to replace my router, but got the same results.
• My ISP changed my IP address, but that didn’t help. As the calls are sometimes working I don’t think it’s a black-listing problem.
• I cannot connect to site with browsers or other cli tools neither.

What else can I try to find the cause of this issue?