It is what I got from my ISP When I get to (approx) 900 incoming / 600 outgoing tor connections the router goes TITSUP.
Go download a dozen high seed unix iso's in parallel via clearnet bittorrent. If it still crashes it's not tor. You didn't say ISP, model of DSL modem and if you searched the net for that model and its firmware rev for other people having problems, and if the firmware is up to date. Some modems suck, especially when in 'routing' mode, or provided by ISP. Reprovision modem to "bridge" mode and install a unix / OPNsense on some old box as your "router"... the box and OS are free. Or pick up a good used modem locally to replace the ISP suck. Whatever you do, investigate things step by step to find the problem first.