Hello,
Could you please confirm whether you’re using the router in bridge mode when connecting the OTD500?
Additionally, please make sure the device firmware is up to date, ideally running the latest 7.15 version. If not, I’d recommend updating and letting me know if this brings any improvements to the upload performance.
Furthermore, the similar (assuming bridge mode is used) topic was discussed here: TRB500: High speed in NAT-Mode but slower speed on passthrough-mode and bridge-mode. Repost
Best regards,