I’d start with getting a OpenWRT-compatible router and flash the OpenWRT firmware onto it. You do NOT need to replace the modem.
Looks like you already did that but with Tomato. Honestly, nevermind then, this comment is redundant.
It took me about 2 hours to do the whole setup with a tplink Archer wifi router hardware, I got it for about $40 used on Ebay.
I’d start with getting a OpenWRT-compatible router and flash the OpenWRT firmware onto it. You do NOT need to replace the modem. Looks like you already did that but with Tomato. Honestly, nevermind then, this comment is redundant.
It took me about 2 hours to do the whole setup with a tplink Archer wifi router hardware, I got it for about $40 used on Ebay.