gpy FTP transfer limit

[kjm]

I'm trying to upload upgdiff_33080-to-39529.dup to the gpy flash for a first time modem upgrade via Filezilla over wifi but the FTP server always halts the transfer after 786432 bytes. I'm intimated by the complexity of using an sd card for update. So hoping a pycom or Filezilla guru might have a suggestion to beat the 786432 limit.

Status: Retrieving directory listing of "/flash"...
Command: TYPE I
Response: 200
Command: PASV
Response: 227 (192,168,4,1,7,232)
Command: LIST
Response: 150
Response: 226
Command: PASV
Response: 227 (192,168,4,1,7,232)
Command: APPE upgdiff_33080-to-39529.dup
Response: 502
Error: Critical file transfer error