Slow VPN with 5G, great with other services
Wes517
Enthusiast - Level 1

I'm hoping someone has answers.

Switched to Verizon home 5G and getting the expected 300/20 speeds regularly on my devices including work laptop, till I go on a VPN. This testing is from 2 PCs (one older desktop (personal) and new work laptop

Desktop gets the 300/20 all the time, set up a virtual machine with VPN and get 69/20, which is fine for that. Shows things are working decently on that VPN.

Work laptop when not on VPN gets the same 300/20 I connect it to work VPN (GlobalProtect) and it drops to 8/1

I take it with me to someone else's house using Spectrum and it's in the 200/30 range on VPN.

 

Talked to my company network team and they say everything is working as expected from their end, the issue is Verizon, Verizon says not their issue.

Tags (3)
Re: Slow VPN with 5G, great with other services
smith6612
Community Leader
Community Leader

GlobalProtect can use a few different types of tunnels. Is GlobalProtect using TCP (TLS) or UDP (DTLS, IPSec) for the tunnel type? Your IT Department may be able to help you determine this. Your speeds might be due to using TCP tunneling.

Alternatively, if the MTU for the VPN is set too high, there might be some packet loss happening. A 4G/5G connection has an MTU of 1472 (1470 is a safer value to settle at) whereas DOCSIS and Fiber (what Charter/Spectrum uses) can carry at an MTU of 1500 (standard for Ethernet), so if you're trying to send packets which are too big, they may get fragmented or dropped. This drops the bandwidth.

If the Firewall on your router is set too high, it may also be blocking the VPN's ability to use UDP tunneling.

Re: Slow VPN with 5G, great with other services
Wes517
Enthusiast - Level 1

Hello and thanks,

It's using IPSEC with a MTU of 1400 that if I change it flips back right away.

I did some ping tests for fragmentation and it is not fragmenting the packets.

I've tried wires with a docking station, wireless to my internal access point, and wireless directly to the verizon box, all get the same results.