So after further invetigating, testing and chatting with the support, looks like there is a workaround and a solution(ish?):
1. THE WORKAROUND:
As other users and the support suggested I’ve tried the sim with using VPN. It looks like this eliminates the CTDs for me. If you want to try this but don’t want to spend on VPN I can recommend ProtonVPN’s free plan. For me it was enough.
I would like to add to this what the support said: “If the issue is resolved with VPN, this confirms that it’s caused by your ISP (internet service provider). There is nothing we can do from our side to resolve the issue.”
2. THE SOLUTION(ISH):
Use Google Public DNS: This was the second thing what I’ve tried and it seems to work. Setting up guide HERE or HERE.
Still not 100% sure but I’m more curious about this one (since it doesn’t require a 3rd party application) if it’s really works for others too or only I had luck this time.
So if you can try, do it and report back here please!