L2 RED

SFOS does support this. https://community.sophos.com/sophos-xg-firewall/f/discussions/134743/red-tunnel---software-v-s-hardware

You can connect a UTM and SFOS perfectly fine with each other. 

And i do not understand your problem in detail. 

A overview of your setup would be good. 

What you dont understand? Do you know what RED means? Its "remote ethernet"? Do you know ethernet means layer 2? My question was - do software UTM support L2 RED?

In general Hardware and Software Images of both platform, are the same. So SFOS on Hardware and on Software is the same. Same for UTM.

So you initial question about SFOS sounds like a configuration problem and not a general statement. 

RED in general is a SSLVPN based protocol, which generates a logical interface. This means, this interface can be bridged to another interface.

Maybe the issue is something else. I will reply in the other thread. 

You are wrong. First, XG and UTM are not the same platforms. I have tested:  Previosly (many years ago) UTM software server works fine with UTM software client, from L2 RED aspect in mind.  But XG software server dont work with XG software client. Only L3 works there. Only hardware XG server works with XG software client, also in L2 RED aspects view. This is tested. ..............Second, RED is not general SSLVPN, its "remote ethernet device", pure L2 tunnel with L3 additional options. I see you dont have knowledge about layer 2 networking. 

You are wrong. First, XG and UTM are not the same platforms. I have tested:  Previosly (many years ago) UTM software server works fine with UTM software client, from L2 RED aspect in mind.  But XG software server dont work with XG software client. Only L3 works there. Only hardware XG server works with XG software client, also in L2 RED aspects view. This is tested. ..............Second, RED is not general SSLVPN, its "remote ethernet device", pure L2 tunnel with L3 additional options. I see you dont have knowledge about layer 2 networking. 

I cannot comment on your behavior, as i do not understand what you mean with software and hardware. This does not make sense to me sorry. 

By software I mean XG or UTM software installed in physical computer, Vmware or Hyper-V. You can download installers from Sophos website. By hardware I mean physical firewall boxes.

So there is no difference between both system in terms of RED. It is the same protocol.

The difference is - in software version L2 RED dont work, in hardware version it works.

That is just an assumption by you. You can verify it by checking for logs and tcpdumps. As stated, there should not be an difference because the OS is the same running on both systems. 

Have you tested it at all? Do VLANs work?

Yes i tested it.