This isn’t the problem here.
OK, let’s keep doing the differential.
- wifi (office): fails
- cell (office): works
- ? (home): works? fails?
Let’s be very specific: what exactly is the “login trouble”? Is it the same “can’t provide a secure connection” message? I’d refer to this as a “SSL connection failure” since you can’t even attempt a login.
Do you also get that at home? Is it the exact same?
Presumably “at home” you mean on wifi, so does this mean you get the same behaviour:
- at home, on wifi: fails with “can’t provide a secure connection”
- at home, on cell: works
It’s important to clearly establish how it’s failing before we start guessing at solutions; we’re still gathering information here.
Does it work via wifi on an independent wifi network?
Do you have a VPN (corporate or otherwise) enabled on your phone?
What does https://clienttest.ssllabs.com:8443/ssltest/viewMyClient.html show from your phone in each situation?
Since this is only happening with your domain name, my guess is you have some sort of HTTP or DNS filtering happening on your client (possibly on your phone, on your home network, or on your work network).
If I punch in your site address into the first URL checker I find, I see it’s listed in a few databases:
Clicking through to the Fortinet page shows they have it listed:
Are you using one of these products at work, home, or on your device?