Hooey is when solutions are recommended before the problem is even identified. You don't have power problems and don't need that expensive APC.
Now, when problems occur, collect important facts. iMac will be a best diagnostic tool since complications from WiFi are eliminated. Start with the lowest level protocol. Each ethernet wire should cause a light to illuminate when interconnected. Typically the light on iMac would be part of the connector. A light on the Linksys would be on the front panel. Confirm this by temporarily disconnecting the ethernet wire. That light will extinguish.
From your description, that connection is probably fine. But more important is an Ethernet wire from Linksys to Surfboard. What does that light report when problems exist?
I believe that the modem is working fine, as I can wire directly to it and get online. All the lights on the modedm light and are solid. When I connect the iMac directly to the modem's port, I get a flashing green light that I am told signifies connection to a PC. When I connect it to the Linksys, the same light flashes orance, whch I was told by a Comcast ech signifies connection to a router. Indeed, when the setup is working, that's what it does. But when the setup isn't working, that light, and all lights on the modem and router, look the same.
That's level one. Now for higher level protocols. You don't describe how the link level is configured. From Safari, enter the address of 192.168.1.1. That should log into either a server inside the Linksys or a server inside the Surfboard. Learn if you can talk to either or both computer. And how IP addresses are being assigned (leased).
When I enter the 192 address, I access the router's setup. The leasing is DHCP or something- I am not at the iMac, but I don't know what it means anyway. I am able to set the router up, but I do not know what the correct setup is for my situation.
These tests are best done when things are working. Then later, if things fail, then you know what 'not working' looks like. Not just for you. Learning this simple test also best advise for others.
I'm here to learn! However, all the lights look the same whether it's working or not. And I reset the router the same way each time, and then it works, until it doesn't.
A better reply would exist had you provided critical facts. Such as what you configure in the Linksys. And what configurations are in the Surfboard.
Please tell me what the critical facts are, and I will report them. I don't know wwhich they are. I enabled MAC cloning. I use WPA and AES. There are a LOT of settings that I don't change out of ignorance.
Also try connecting iMac directly to the Surfboard. Enter the 192.168.1.1 address or what even address would apply to learn what is or is not observed.
Haven't tried this, but will.
Your problems are typically not environmental. But the number of possibilities is enormous - maybe as many as 100 different things might be 'fixed'. A better solution first defines a problem by learning what exists before fixing anything. First learn what you have when things work (ie lights for each ethernet connection). Then repeat those inspections when a failure happens. Also report how the Linksys and Surfboard are configured. The iMac and Safari talking to 192.168.1.1 (or whatever address is configured) will go a long way to identifying which of maybe 50+ items is problematic.
Problematic power anomalies happen maybe once every seven years. Would not cause those three hickups. A typical transient may damage grossly undersized protection in an APC UPS. But would be too tiny to overwhelm superior protection already inside the Surfboard, Linksys, and iMac. That most expensive recommendation was based only in advertising generated myths. Will do nothing for your problem.