Break trunk LACP without losing attached DHCP reservation

You could export the config via Import/Export, giving a XML file. The file can include your Interfaces, VLANs and also DHCP server.

Then you adjust your config. 
Then you edit your XML file and re upload it to the firewall.

See: community.sophos.com/.../sophos-firewall-interface-vlan-migration-via-xml-import-export

Unfortunately it doesn’t seem to work. With this you have to unbound the ports first and doing so results in losing all DHCP configurations

Yes, but the config would be stored in your import/export XML file. So you would upload it again. 

Ah. That link was talking about exporting interfaces only ? I didn’t see dhcp in there 

Ah. That link was talking about exporting interfaces only ? I didn’t see dhcp in there 

Yes - it was just an suggestion, how to approach that. XML Import/export supports everykind of approach. 

Ok I’ll look into the options available. Trying to export everything seemed to just crash unfortunately 

How can an EXPORT crash something on your firewall?

You sure mean your subsequent import after editing?

The export itself crash. As to how I wouldn’t know. 

I never had a "crash" when exporting from XG/XGS systems. What do you mean exactly?

The export itself doesn’t go to the end. It never finishes. The process does not finish. 

not sure I understand your question tbh. 

Did you try another browser? or another PC-System for the download?

That is a much more precise and helpful description as "system crashed when exporting". This sounds like "system is not usable anymore after exporting" or "system hangs", which was not the case.

So please, try to describe your observations as precise as possible. Thank you.

Sure. Maybe try to apply the same to your question. 

it is not super useful information to answer « it never crashed for me. »

It is likely not crashing, instead it will take ages to export a fully configurated firewall with all XML files. That is the reason, you expierence this kind of "crash".

But only exporting interfaces, VLANs and DHCP should be fine for your goals. Maybe also including NAT / firewall rules as well.