first:
-> TCRP ( same for ARPL ) Always use full size DSM PAT files when building loaders.
For DS3622+ or DS918+, 7.1.1-42962 U1 (with update 1)
Corresponds to the final version with full size.
In particular, in the case of DS923+ / DS723+ / RS4021xs+, 7.1.1-42962 U5 exists in full size.
If you go to the path below, PAT files that exceed approximately 300M are such files.
https://archive.synology.com/download/Os/DSM
After that, you need to additionally install the required SMALL Update version.
After the Small Update version is installed, FRIEND proceeds with RD automatic patching.
second:
-> You don't have to use the UEFI version of IMG to boot into UEFI.
Legacy versions are also compatible with UEFI.
If you have problems with the legacy version of IMG, I know that the workaround is to use the UEFI version of IMG.
This part borrows the image produced by pocopico as it is in M SHELL, so I don't know exactly how it works.