Slow (synology quick connent to) speeds

My (synology quick connect to) speed uploading to my offsite synology S220+ plus were running about 1.5 MB per second over the past year. last week i updated to the new firmware and the speeds to the nas were running 21 MB per second. this week they are running 500kBs. my internet speed where the nas is located is 300 MB down 300 MB up. The location where the computer is that I am uploading from the PC is 500 MB down 300 MB up. Both are hardwired . No other changes to computer/nas. any suggestions plesse? ps I am getting approx 4MBs from my phone (wifi) when using the app on the same network as the computer in my office (off site from the NAS & not through synology quick connect).

Update. Synology mysteriously now loading at 21MB/s again.

James, whereas this is normal to be expected behavior, I found ways to improve this.

Firstly, WIFI is never as fast as your connected hardwired LAN. WIFI with it’s error correction and retransmitting and variations due to location, does not even give the consistent speed it boasts.

I do a lot of work from my laptop which gives me decent speeds, but if I want to transfer large files back and forth, I turn off my laptop WIFI and directly connect my laptop NIC into the same switch as my NAS with a long network cable.

Yes, it is a bit annoying having one long CAt5 cable sitting around and such, but it will give you much better speeds for the big off loads.