As they say: it is always DNS.
There are tools to test your DNS. Do this before you do anything else.
Malfunctioning DNS is responsible for a ridiculous % of connection problems. Use 1 server of your IPS and 8.8.8.8 (Google) or whatever other public DNS performs the best from your location as the fallback.
I appreciate all advice, but I don’t really understand what this means. What is an ‘IPS’- Intrusion Prevention Systerm? I work from home, not within a business network.
As I said in my previous post, I followed the directions posted by @BigT (thanks again!) and changed my DNS setting from “Obtain DNS server address automatically” to “Use the following DNS server addresses” and inputting the Google DNS addresses 8.8.8.8 and 8.8.4.4. This solved the problem.
My question now is, can I continue to use the Google DNS indefinitely? Are there any drawbacks to doing so?
Also, just out of curiosity, why would the “Obtain DNS server address automatically” setting suddenly start to sporadically fail when it always worked flawlessly in the past?
Yes you can. The only drawback is if your set the DNS to google 8.8.*.* then take that machine/laptop overseas. Now all your DNS queries are stupidly hopping the globe slowing things down. Beyond that, it’s probably fine.
Thanks 
Sorry, IT (ha!) is rife with stupid acronyms.
DNS - domain name servers, a bunch of servers that translate “boards.straightdope.com”
to something your NIC (Network Interface Card: the chip that talks to your physical network connection: cable or wireless) understands, an IP address. (Like 127.0.0.1 for your computer)
Your ISP (internet service provider, the company that connects your house to the wider internet) most likely provides you with 2 or more such servers, a primary and a failover. The problem is that both those servers are set up and maintained by the same people: chances are they will fail together. That is why I advise you to keep the first one (a short, fast connection to the DNS is preferable) and set up a DNS from a different company as your secondary or tertiary.
(Typically 8.8.8.8 works in most places and is easy to remember— equally typical is that it wil not be the fastest where you are)