I'm using the same old NAS with SW-Version V4.81(AALS.1) and I made it work in LE10 with the following settings in Libreelec:
Section 'Libreelec' /'Services': Minimum supported protocol SMB2, Maximum supported protocol SMB3
Section 'Services'/'SMB Client': Minimum protocol version SMBv1, Maximum protocol version SMBv3
Strange setting but successfully working with LE10.0.0 and LE 10.0.1!