Hi everybody,
I’m a complete newbie regarding tailscale, servers even networks and such so please, go easy on me :D. To make the story short, I’d like to to be able to remotely connect to my home PC (so far I am using Tailscale + Sunshine/Moonlight), but when connected, I also need to be connected to my school’s network via VPN (Cisco Secure Client - provided by the school) so that the licenses for the software such as CAD work. Hope I explained it well. I tried to look around for solutions from people in similiar situations but so far I’ve found nothing. Any input, ideas or help will be much appreciated. Also I was wondering if utilizing Proxmox would help somehow? Creating a container with Tailscale, create a VM to run the (CAD and such) software with the VPN and…
Yes it’s actually explained here: Digital Nomad VPN Tutorial using Wireguard or Tailscale and Can I use Tailscale alongside other VPNs? · Tailscale Docs
You can try connecting to your school VPN on your home PC, then run tailscale there with the --advertise-routes=192.168.0.0/24 flag (use your home network subnet) and use your home PC as an exit node for tailscale.
Not sure it will work, but you can try.
EDIT: Maybe your need to use --advertise-routes='CISCO VPN Subnet", not your home subnet. Somebody else should jump in to help.
Yes it works. I have Tailscale running (and connected) on my MacBook, while using Wireguard to connect to one of my self-hosted vpn (hosted on a vps) and it works without issues.
I’m using Pure VPN with Tailscale it’s fine. But I am on linux mint.
It depends on the Cisco AnyConnect Client configuration, it will typically block other vpns and local subnet access PITA even for hyperV/local virtualization.
A tinkering project would be to create a Cisco vpn docker with Tailscale and offer it as exit node 
And for at least an useful tip if you encounter weird errors like some thing working and some not you may have some mtu problems. Fixable but annoying as a beginner.
What about getting both to work on a Synology NAS? Has anyone done this? I use Tailscale to connect my primary NAS to my remote backup NAS at a relative’s house, and would also like to also use a VPN on the primary NAS for other things.
Don’t even need to advertise routes if you can route all traffic from a tailscale node over a VPN and just use it as an exit node
Similar experience here. I had this setup for secure work, had to disconnect from work to access any other connection including LAN resources. Inside any anyconnect there is a policy to allow/block dual access and most issuers choose block as more secure; client user has no choice.