Connection to Azure Redis is not working from some machines

We have a solution using Azure Cache for Redis. This is working fine in our Dev environment (I'm attaching logs for working connection: RedisGoodConnection.txt), but we can't make it work in our Acceptance environment (Attached "RedisBadConnection.txt).
The only difference that I can think about is firewall rules, but firewall is open. In fact in the logs I can see that the connection is done, but TLS handshake is not happening.
Some things that I've tried, with no result:

• Bypassing Certificate validation (config.CertificateValidation += (a,b,c,d)=> true;)
• Enabling TLS 1.2 for .net framework (as suggested here: https://johnlouros.com/blog/enabling-strong-cryptography-for-all-dot-net-applications). No result either.

Any idea on how to troubleshoot this will be welcome 8·)

This is a code demoing the error (redis url and password are dummy values here):

          var redisConString = "oneazurerediscache.redis.cache.windows.net:6380,password=myprivatekey,ssl=True,abortConnect=False,sslprotocols=tls12,connectTimeout=30000";
           var redis = ConnectionMultiplexer.Connect(redisConString,Console.Out);

Packages used are the last version available:

 <package id="StackExchange.Redis" version="2.1.58" targetFramework="net472" />
  <package id="StackExchange.Redis.Extensions.Core" version="6.3.5" targetFramework="net472" />

RedisBadConnection.txt
RedisGoodConnection.txt

Start by comparing RedisBadConnection.txt with RedisGoodConnection.txt, then reproduce the issue with the provided ConnectionMultiplexer.Connect example using StackExchange.Redis 2.1.58 on net472. Investigate the differing Acceptance-machine TLS handshake behavior and document a verified cause or fix when the connection succeeds there.