Speeds through the floor

[Freefaller]

I have been using Filezilla with my rapid seedbox for several years now and it has been great. I use explicit ftp over tls. I have been downloading at good speeds for my connection for all of that time. A 1 gig file might take 10 or so minutes which is fine by me. It usually downloads between 1.5Mbps to 4 or 5 Mbps.
For the past 5 weeks my download speed has dropped to anywhere between 10 Kibs to 50-60 KiB/s.
A file that used to take 10 minutes is now taking 10 hours.

When this first started happening the speed would instantly ramp up to The usual 1 - 5 Mbps and then slowly over a minute or so, drop down to the ridiculously slow 10-60 KiB/s. That is no longer the case...now it just starts with a "?" and then after about 10 seconds begins the 10-60KiB/s download speed.
Nothing has changed at my end. One day it just changed and has basically made ftp transferring useless.

I have contacted my isp and have done multiple checks with them. My connection is strong and averages about 90Mbps. They are adamant that they are not shaping my connection and went so far as to tell me that they are not legally allowed to do so.

I purchased another Seedbox to test if the rapid one was at fault but it made no difference. Same slow speed. I have deleted, cleaned and reinstalled Filezilla several times but to no avail.

If anyone has any advice or could at least help me to understand WHY this has happened I would greatly appreciate it.

It is doing my head in!

Many thanks for your time.

[botg]

Could you please try downloading from a different computer, or a different location?