Ah, are you (and the other respondents) understanding my situation fully?
I understand the situation and I think most of the other respondents do too. The issue is if you set manual DNS on all of those client machines, first of all, if you do need to change DNS settings you'll need to do it on multiple devices. Secondly, if you set the DNS manually to something on the internet then all of your clients are individually going to trouble a DNS server on the web (so let's say probably at least 20ms or so away) for every non-cached DNS record they need. There is a good chance most of your clients will hit the same webpages at frequent times (google, youtube, Microsoft, Windows Update, facebook, whatever).
Not only this, if your ISP is good, then their DNS server should be the best (or very near to the best) external DNS server for your devices, because it is doing a good amount of caching and should respond in the fastest time as it will be in your ISPs network (so very few hops away).
Your router will obtain the ISPs DNS servers automatically during its own DHCP process and therefore this will always be kept up to date with the latest DNS severs your ISP is using.
By setting the clients to ask your router as the DNS server, your router will be asking your ISP DNS server for the DNS query on behalf of your clients, however, it will probably be doing some caching itsself, so while in theory asking your router to ask your ISP (rather than just asking your ISP) may introduce a very minimal amount of latency (maybe 1-2ms tops), the caching means that if your router has already resolved the record for other devices on your network and has them cached, when the next device on your network comes along and asks for the record, it takes 1-2ms (to ask your router), rather than that 20ms to go and ask your ISP.
Even if your router does not do caching, then the added 1-2ms is worth putting up with because remember the router is automatically updated with the latest IP addresses for your ISP DNS servers and will prevent the situation occurring where your ISP changes the IP and you suddenly find web pages not working and you have to go round changing the settings manually.
The best is to have an actual DNS server running BIND or whatever in your house (again, using the ISP DNS as a forwarder) but we are going to presume you don't have a dedicated server, therefore, the router is best served as the DNS server for devices on your network.
All this theory completely breaks down if your ISPs DNS servers are carp, but then if your ISP is running carp DNS servers then they are probably a carp ISP and so all is lost anyway. It also breaks down if your router is particularly rubbish at acting as a DNS server/proxy, but this is quite uncommon.
By the way the comment about glitches in steaming and DHCP makes absolutely no sense at all, I would advise leaving DHCP turned on and setting reservations if you need to. If DHCP on your router is known to cause glitches in streaming, buy a better router, or quite like above with DNS, run a dedicated DHCP server
Zen 8000 Pro
Edited by Pipexer (Sat 15-Mar-14 13:52:02)