Set up SOCKS5 proxy (e.g. github.com/rofl0r/microsocks) on the nearest router and configure router's firewall to drop all outgoing packets whose TTL is near 128

Set up SOCKS5 proxy (e.g. github.com/rofl0r/microsocks) on the nearest router and configure router's firewall to drop all outgoing packets whose TTL is near 128 (Windows). Then configure FoxyProxy in Firefox or Chrome to use your SOCKS5 proxy. Windows will think it's offline, browser and other apps which are aware of your proxy will work fine.