Qt online installer is too fragile

Qt online installer is too fragile when a mirror malfunctions.
Even though there are tons of well-functioning mirrors, Qt online installer always picks same broken mirror(maybe top prioritized mirror?).

For instance, mirrors-wan.geekpie.club is broken for several days, which results into disabling installer at all in my region.

I think it should provide one of next two features at least,

• automatic fallback to other mirrors when network error occurred
• customize(select) default mirror by user

By the way, about second one, it is very confusing that Qt online installer always picks default repository from Qt website even though there are settings for user repository.