I'm looking for a single stick of RAM for a Synology NAS (DS220+); happy with 4 or 8 GB.

SODIMM DDR4, non-ECC, 2666 Mhz

I've read mixed things about how fussy these NASs are with the RAM, so looking for a stick that is likely to be compatible (as otherwise I'll have to on-sell it).* 

Thanks in advance.

* These are some of the models recorded elsewhere as compatible (I assume different capacity variations would also work):

• Kingston KVR26S19S6/4 4GB DDR4 2666 SODIMM
• Crucial CT4G4SFS8266 4GB, DDR4, 2666 SODIMM
• Crucial CT8G4SFS8266 8GB DDR4 - 2666 SODIMM
• Samsung M471A1K43CB1-CTD 8GB DDR4 2666
• Samsung M471A5244CB0-CTD 4GB
• Synology D4NESO-2666-4G