VPN connection to remote server slowing internet dramatically - no ethernet

So someone i work for has set up a server on his end so that we can transfer media more efficiently. I can get more details on his setup if needed but basically the gist of it is this -

I have ATT fiber and outside of this whole VPN thing, i get close to the full speeds over ethernet and still like 800+mbps over wifi. When i open the VPN connection and connect to his server it slashes my wifi speeds for my entire computer down to like 150mbps and the download speeds from his server directly are basically that same 150mbps. And the VPN straight up wont connect at all if i try to use ethernet (and i believe my computer completely ignores the Ethernet when i plug it in when i’ve already made the VPN connection using my wifi card).

My understanding is that the VPN is like a tunnel to his server and shouldn’t impact my overall internet (meaning when i try to access things aside from his specific server), so why is it impacting the speeds for my entire computer so dramatically? Is there anything i can do on my end to troubleshoot this? He mentioned something about adjusting Network Priority?

I want to be able to use Ethernet when accessing this server. I want to be able to get somewhat remotely close to my normal speeds when the VPN is connected. I understand that VPNs can negatively impact speeds, but i figured it would just be for only when i’m accessing the server. I don’t pay for a VPN or anything, it’s just the windows built in VPN connection thingy.

It was set up by a “professional” on his end and i can give more details if needed. The VPN type is “L2TP/IPsec with pre-shared key”. The authentication is “MS CHAP V2”. I believe the share type he’s using is SMB, though i’m not sure on that. I’m using Windows 10.

Talk to me like a moron because i dont have a ton of experience with networking, VPN etc.

My understanding is that the VPN is like a tunnel to his server and shouldn’t impact my overall internet (meaning when i try to access things aside from his specific server), so why is it impacting the speeds for my entire computer so dramatically?

What is the upload speed of the other end of the tunnel? Just because YOU have fast internet doesn’t mean they do…or they are throttling.

It shouldn’t affect things outside of transfers to/from that other server if the VPN is set up correctly with split tunnel. If it’s not set up with split tunnel, then you (they) need to configure that.

I want to be able to use Ethernet when accessing this server. I want to be able to get somewhat remotely close to my normal speeds when the VPN is connected. I understand that VPNs can negatively impact speeds, but i figured it would just be for only when i’m accessing the server. I don’t pay for a VPN or anything, it’s just the windows built in VPN connection thingy.

How you connect to your local network has nothing to do with your VPN connection to another network. Your local network gets you TO the internet.

It was set up by a “professional” on his end and i can give more details if needed. The VPN type is “L2TP/IPsec with pre-shared key”. The authentication is “MS CHAP V2”. I believe the share type he’s using is SMB, though i’m not sure on that. I’m using Windows 10.

There’s a bit of overhead with this type of VPN connection, but the fact of the matter is, the VPN needs to be configured correctly for split tunnelling and the other person’s upload/download DOES matter if ALL your traffic is going through the VPN tunnel.

Definitely sounds like OP desires a split tunnel but is not getting it. It’s a client-side setting, and not difficult to implement. Also VPN overhead can absolutely be a thing - cryptography done with modern VPNs can and does impact performance. In most situations it’s unrealistic to expect anywhere close to full theoretical physical connection speeds via VPN.

What is the upload speed of the other end of the tunnel? Just because YOU have fast internet doesn’t mean they do…or they are throttling.

Their internet should be same as mine - 1 gig. I’ll check with them about the split tunnelling.

How you connect to your local network has nothing to do with your VPN connection to another network. Your local network gets you TO the internet.

Yes, that’s what i figured. So i have no idea why simply connecting to the VPN would drop my overall internet speeds from 850 to 150 for ALL of the traffic on this computer, not just stuff i’m accessing from the server. Or why it would disable being able to use an Ethernet cable from my PC to router. Are you saying that just making this VPN connection is tunneling ALL of my traffic on this PC through that tunnel?

Yeah im sure it’s something on his end. I’m not expecting full normal speeds from the VPN connection itself, but i am expecting it to not be taken down by a factor of 1/8 of the original speeds, and i am expecting my normal internet to function normally, as i’m not trying to send all my normal traffic through this VPN or whatever.

Or why it would disable being able to use an Ethernet cable from my PC to router.

A VPN connection can’t do that.

Are you saying that just making this VPN connection is tunneling ALL of my traffic on this PC through that tunnel?

That’s what it sounds like. If you go to a website like https://icanhazip.com does it show YOUR WAN IP, or your “professional’s” WAN IP?

A VPN connection can’t do that.

It does though. I’ve tested it many times. Or it’s just throwing something off in my network adapters or something.

scenario a - i’m on wifi with the VPN disconnected and plug the Ethernet in. It instantly switches to ethernet as it should normally and the speedtest reflects that with faster than wifi speeds, and switches back once cable is disconnected.

b - i have ethernet plugged in with VPN disabled and it’s functioning normally. I enable the VPN and the VPN connects. Ethernet is no longer recognized and it switches to wifi and drops speeds to 150-160mbps.

c - i have the VPN connected with wifi as the connection. I plug the ethernet cable in and it does nothing and does not switch to ethernet connection and ethernet shows “No Internet”

That site shows my coworker’s IP, not mine.