Really slow transfer from Admin PC to Laptop

I have 2 desktop computers and one laptop on a network, all three are also part of a Homegroup.

When I try to copy files from the main Admin PC to the laptop it slows down to less than 15KB/s. I thought perhaps it was the wifi reception but even when connected with Ethernet it's still terribly slow to the point that a 300MB folder takes 2 hours (estimated time). I end up cancelling the transfer sand sometimes windows explorer ends up crashing.

However when I copy files from the second desktop to laptop it is normal speed. No lag, no glitch.

All the files I tried to copy where share, available to Everyone. Everything else works fine, streaming video and music from the main admin PC is flawless, I just can't seem too transfer files from the main Admin PC to the laptop.

admin pc->laptop:slow
second pc->laptop:fast

correct?

yes, thats correct.

admin pc->second pc : fast or slow?

normal speed, but only if I'm on the admin PC. If I'm on the second PC trying to copy from the admin PC it doesn't work.

I should clarify that it's not going slow, it's stuck on Copying as if it's on queue, doing calculations and all that stuff. If I leave it for 10 min then it starts transferring files at around 7 kB/s, other times windows explorer just crashes.

admin pc->laptop: done from laptop
admin pc->laptop: done from admin pc

Does not work, stuck on copying as if it's on a queue, does not matter if I'm on the admin PC or laptop.

laptop->main pc: done from laptop
laptop->main pc: done from admin pc

Transfer only work if I'm on admin PC copying from laptop.
Does not work if I'm on laptop trying to copy to admin PC.

As for the laptop and second PC I can transfer files fast between both, it doesn't matter which computer I'm on.

For large files you are probably faster to copy to a stick or external disk and then from there to the other PC

500mb isn't large at all. I've been copying 20+ GB files from the second PC to the main admin PC frequently, takes about 15 min.

Could it have to do with Read and Write. I only have it on Read for the main PC because I don't want other users deleting folders.

Try to do this:

copy a file from second pc to laptop. Once done from laptop, once donce from second pc.
copy a file from laptop to second pc. Once done from laptop, once donce from second pc.

Both actions mormal speed?

all average the same speed.