Sorry, newbie here with basic questions.
Is there any advantage in the hardware of a wireless router (antenna, etc) that a laptop doesn't have? Would I need to attach external wireless hardware to a laptop, to make it comparable to that of a wireless router?
If I were to use a laptop, would openwrt be the best software to use? Is openwrt specialized for hardware with low system resources, such that there would be better router software to use on an x86 machine?
first major cons for me would be power consumption of a laptop running 24/7 vs small wifi router
I suggest you read this thread: Converting a surplus x86 into an OpenWrt router
Using an old desktop PC makes it easier to add additional Ethernet ports, but the general discussion should apply. Considering the power usage vs buying a new (used) device to get your feet wet with this type of projects is probably not the really discussion here.
A lot would depend on the WiFi card in the laptop. Is it capable of being used as AP. Does you “old” laptop have fast ethernet or gigabit speed. Then what type and speed internet do you have. The above thread should give you a good idea.
using a wifi device with external antenna will probably give you better signal than the laptops builtin wifi... depends 
software wise, openwrt should be fine and give a good/familiar ui, but aside from features there should not be significant differences.
power consumption of my laptop in idle (with wifi and display) is around 7 watts according to powertop. about as much as a typical router. so, again, depends on your hardware.
Most laptop wireless cards are designed to be used on a single band at a time, and as clients, not as APs. Even though labeled as "dual-band", that means 2.4 GHz or 5 GHz.
Yes the gain of the antennas on a SOHO router are often significantly greater than that of a laptop, and sometimes the RF power output is greater as well. Multiple antennas can provide better performance (but that is no guarantee that a three-antenna box works better than a two- or one-antenna box).
OpenWRT works just about the same on a multi-core x86_64 as it does on a tiny embedded processor. Same ease of use for many home/SOHO setups. I'd recommend that you install and enable irqbalance if you're running it on a multi-core system.
Yes there is. Most laptop wireless cards do not perform Access Point mode (i.e. you cannot make it a wireless router). Also, power consumption has already been noted. A device with a hard disk drive and monitor will inevitably consume more power.
As @drbrains said:
Likely; but it depends on the WiFi card installed already.
If you intend to re-purpose the device for use only as a router (maybe a NAS or other network-attached device), yes. If routing won't be used, there are desktop distros (e.g. Lubuntu) made for low-resource machines.
I'm not sure I understand your wording here (it sounds like you're concerned that OpenWrt is "underspec for an x86")...but I've seen OpenWrt run with 200 MHz of processor and 24 MB of RAM, I would define that as "low system resources."
maybe some dont. have not seen one thou
See discussion here: Which PCIe WiFi card works on x86 LEDE? about wireless AP cards in PC (laptops)
Is openwrt specialized for hardware with low system resources, such that there would be better router software to use on an x86 machine?
I'm not sure I understand your wording here (it sounds like you're concerned that OpenWrt is "underspec for an x86")...but I've seen OpenWrt run with 200 MHz of processor and 24 MB of RAM, I would define that as "low system resources."
What are the links for?
I'm very familiar with all 3 Wikipedia pages.
EDIT: OP probably hit reply under post instead of thread. Good list of links, though!
I was asked what I was asking. I doubt anything would be better suited, but if OpenWRT is specialized in router hardware, maybe another routing software would be better for a laptop. However I'm still on the fence about using an old laptop or getting a decent router. Thanks for everyone's replies.
Oh...I thought that's what you meant to clarify...
I was attempting to explain that Linux Kernel is the same, so at least if the distro is Linux-based, you will find little difference in "specialization."
Your seeking another distro should be on preference to run on the laptop, not perceived "suitableness" for an x86 machine.
Things to consider when using a notebook as router (this does not apply to better suited non-notebook x86 hardware), I'm concentrating on hardware specialties
Extending features via USB is not really an option, you need USB3 for mostly decent ethernet performance (which would require rather recent notebooks) and the situation for USB wlan cards in AP mode and 24/7 operations is even more dire (only ar9170/ ar9271 (both EOL for years) really support AP mode (including powersaving clients) properly at all, number of concurrently connected clients is limited to the 4-8 range (not enough RAM on the wlan card itself), USB devices will often overheat in active 24/7 operations, even then stability is abysmal (stalled connections for no reason)).
Well selected x86 hardware can be a good choice as a routing platform, most notebook hardware however is not (not enough PCIe ports for 2+ ethernet- and 2 wlan cards). On the other hand you can find decent dedicated (concurrent dual-band, 1 Gbit/s ethernet) router hardware (mt7621) starting around 40 EUR/ USD, over the medium target around 70-120 EUR/ USD (ipq40xx, entry level mvebu) to the highend consumer hardware (ipq806x, mvebu) around 150-250 EUR/ USD. Decent x86 for router uses starts in the medium 250 EUR/ USD range, depending on your needs.
Personally I'd consider classic hardware routers to be a better choice in the classic home environment at up to ~300-400 MBit/s WAN speed (yes, mt7621/ mvebu can deal with up to 1 GBit/s, if additional services (VPN etc.) can keep up with that is another topic), above that and/ or with additional requirements the cards shift towards x86 quickly (especially if you can outsource wlan functionality to dedicated hardware).
I have a netbook as router. HP mini 2gb ram.
Some points to consider as negative points:
Another problem with using a laptop as a router is that most PC wireless adapters, even if they are capable of AP mode, are not designed to act as an AP on the 5GHz band. They are set for a world regulatory domain which has a "no initiate radiation" policy on 5GHz that doesn't allow it to do anything other than connect to an existing AP.
Based on your input, and searching the web, I ended up writing the following post:
http://mekineer.com/dokuwiki/doku.php?id=information_technology:2018_ideal_network
Highlights:
" My ideal network would have a fanless mini pc with gigabit ethernet ports, connecting two dual-band wireless access points for the 8 house mates. The need for two access points is because all wireless bands are crowded in nyc, such that any channel can't handle much. "
" I chose a simpler solution than setting up “the ideal network”. I had a 50 foot ethernet cable on me. I ran the cable from the router to my room, since I only use internet from my desk. I suggested others do the same if they had issues (which would also reduce the wireless load).
So, what to do about the now occupied ethernet connection, that used to connect the Buffalo router for my local lan with the printer and second laptop? I used my local lan to share files between the laptops (so as not to add load to the wifi). In a past residence I had a double NAT set up with the Buffalo, but it is old and only has 10/100 ethernet (Speedtest website clocked 225mbps download). Should I abandon my local lan and buy a gigabit switch to tie in everything to the house network?
Instead, I chose to keep the local lan ethernet cable next to the laptop, and manually switch them as needed. It's not ideal, but I may be moving soon, and I don't know what my needs will be in the future. I'm using a program called NetSetMan, to quickly change my ethernet settings to the manual configuration I'm using on the local lan. "
First off: you are making your own thread go completely off topic!
I will go along a bit and have to ask: how are you connected to the internet. The way you picture it, you only have a cable/fiber/dsl Modem. I don’t know in nyc but most providers would provide you with some kind of (wireless) router plus modem combination.
It could be the case the you have a modem only solution in which case I suggest you to buy a cheap second gigabit (OpenWRT supported!) router. Shouldn’t cost more than USD 20. Which in NYC I imagine doesn’t get you very far in terms of food and drinks.
Yeah sorry to go off topic. We have an Arris Touchstone TG1672, which is a modem plus wireless router combo. A second access point could be added, I guess, to this existing router. However, if I get the chance I'd look forward to having a router made from a fanless mini pc with gigabit ports, such as a available on aliexpress for $100, and add an ssd and openwrt. I'm sure the ISP routers have a bridge mode, or whatever mode it is to pass along traffic to your own router.
Why don’t you run the cable from LAN to LAN and have your Buffalo router act as a switch and AP (with DHCP disabled). That will “cost” you wired download speed because you said the Buffalo is only 100mbps. In case you really need that speed you could always choose to manual replug the cable.
The benefit would be that you can have the other LAN ports of the Buffalo for your desktop, maybe laptop and printer. Plus you would have a second AP which you can run on a different channel if you want and have a zero money solution.
Getting a dump gigabit switch between your cable and the Buffalo gets you gigabit wired speeds and still have slower devices (like your printer) on the 100mbps ports of the Buffalo. And still have the extra AP. Dump gigabit switches should be “cheap” to find.
If you're heading this direction then I recommend you get a smart switch. The zyxel 24 port is $100 on Amazon and very good. That's a lot of ports, which is what you want. The tplink sg-108e is not as good but ok, costs around $35
Dumb switch is not a lot cheaper than the tplink.