First of all, the internet is VDSL2 over telephone cables, running from the demarc is a cat3 "I think" aluminum cable, to inside my house, where I connect it to a splitter then to my current router, I've two that I use "switch between sometimes for no reason" a tplink VR600, & A dlink 2888A, of course neither support openWRT, my current internet speed is 30/5, & I'm planning to upgrade soon to a 80/30 or maybe a 100/50 Mbps
1-is it optimal to use either of my current routers as a modem only & a new openWRT supported router for WAN/LAN? or should I buy a modem only unit in addition to an OpenWRT supported router?
2-which budget router that supports openWRT should I go for, I plan to use SQM "CAKE auto rate", since I'm mainly using my internet for gaming
3-if you recommend a netgear 7800 or a tplink C6/A7, do either of those support PPOE over their wan port?
Optimality is in the eye of the beholder....
- question: do you want/need as few devices as possible? In that case you might want to look at all-in-one modem routers. OpenWrt supports both older lantiq xrx200 and more modern vrx518 based DSL modems.
The xrx200 ones are typically matched with a slow enough CPU to make plain routing at 80/30 or 100/50 already a challenge, let alone traffic shaping (sqm/cake-autorate)
The vrx518 ones like e.g. an AVM Fritzbox 7520 or 7530 (but be careful AVM markets different SoCs under the same names) are often paired with far more beefy CPUs and might be able to service all your router needs.
However, you might want to use two devices for other reasons (e.g. I use a FB7520 running as bridged-modem under OpenWrt, placed to minimize the length of additional telephony wiring inside my flat, and then use a cat6 cable to feed my promary WiFi-router, placed for decent WiFi coverage).
So you need to figure out what you want, maybe, if your existing modems can be configured into bridge-mode all you need is an OpenWrt capable router.
At 100/50 with sqm/cake-autorate you certainly will leave the comfort zone of oldish MIPS based SoCs, but maybe IPQ40XX might be powerful enough?
I think none of these support power over ethernet (PoE) on any port (but you can always use a combination of dedicated power injector and power splitter, but beware*). If you mean PPP over ethernet (PPPoE), then yes all OpenWrt capable routers will support that.
Side-note many countries are switching from analog telephony to using all-IP VoIP and in those cases splitters might not be needed anymore. Where are you located?
sorry I meant PPPoE, & I'm located in Egypt
Ah, no idea about the analog/VoIP telephony developments in eqypt... but that s probably not too relevant anyway. So yes, PPPoE is something that OpenWrt does in software, so any OpenWrt router will allow you to use PPPoE...
About what router to recommend, all I can say is that xrx200 seems to slow (I tried to use a BT HH5A under OpenWrt as all in one modem router under OpenWrt, but that did not even allow 50/10 Mbps with DSL, PPPoE, NAT, firewalling, WiFI and SQM), the IPQ4019 of the fritzbox 7520 looks much more solid, but I have not even tried to operate it as all in one modem router. My primary router is a turris omnia (from the crowdfunding campaign) which is a great piece of kit, but it always was a bit pricy and by now it still is pricy and getting long in the tooth.
what about the C6, it has a dual core cpu, right? would it be enough for my bandwidth? it's hard to get fritzboxes here