Your Android sync should not be annoyingly slow. I synchronize about 3 GB per day and it takes less than 4 minutes. I back up to my PC from my cell all of my SMS text messages which are several gigabytes and it flows pretty quickly between my cell phone and my laptop.
I think I saw that your connecting via TCP Lan which is what you want for the best performance. Can you check if the packets are going directly from PC to phone and not routing through your router via UPnP?
As a quick test you can always substitute the IP address for your laptop on the cell phone rather than using dynamic and see if by pointing it directly to the PC that needs to sync to if the speed improves.
This should not be necessary but you could use it as a process of elimination.
You can also run a bandwidth performance test between your cell phone and the PC using iperf. It measures throughput between two Network nodes and should give you an accurate measurement if you test it in both directions.
There is an iperf2 app in Google Play. It runs on Linux and Windows too. You should give you much better bandwidth as a verification that you don’t have a communication problem between your cell phone and the server.
If you prefer I prefer three there is a program called pingtools in the Android store that supports iperf3.
Iperf2 and iperf3 are not compatible with each other so they must run the same version on both sides.