FWIW I think that depends on the client. I use OpenVPN over TCP with Linux and Windows clients for managing a remote customer location with no issues.

However, Android doesn't work at all. I suspect it's a configuration issue, but the lack of meaningful logs makes it damn near impossible to troubleshoot.

If you happen to run an all Mikrotik routing environment, the SSTP tunneling works well. I have a customer with hundreds of Mikrotiks out in the field, each with an SSTP connection back to a cloud-based Mikrotik installation for remote management/monitoring.

SSTP supposedly works with Windows clients too, though I've never tried it.