I don't know about the V30, but I had a V20, and it connected (and stayed connected) just fine for months. And the router I use is the second cheapest one on the market (I don't buy Trendnet.) So it's not LG. If your carrier has a brick and mortar store, see if they can help you. Most cellphone stores have in-house wifi, even if they forget the connection after they fix what's wrong with yours. (They don't want you sitting outside connecting to their LAN - it's a security risk.)
I've also had a few other LGs, going back to the first flip phone with a camera. And never had a problem with wifi with them.
The problem is that troubleshooting a wifi problem can be impossible enough if you're there - doing it remotely like this makes it just that much more difficult. But, as Joe said, check to make sure that your DHCP (not DNS) server (in the router) has at least one open slot. (By default, all 253 are open, but some people, who understand how things work, restrict them to what's needed. So if you have 3 devices plus your phone, and you have 2 connected, the phone has no trouble connecting - it gets that 3rd slot. But if all 3 devices are connected, then you try to connect the phone, there's no IP address for it. [The DHCP server assigns IP addresses to devices as they connect.])
Of course there are many other possibilities. (One we can eliminate is that the phone can't handle the form of encryption. Some phones have a problem with some implementations of TKIP. But that phone connected to that router, so that's not the problem.) Also, place the phone on the router and try to connect. (I'd be amazed if that's the problem, but if your luck is bad enough, you could have gotten 3 phones in which the wifi antenna became disconnected after a while.)
Facebook
Twitter
Instagram