Idk what else can cause those red spikes apart from problematic and unstable connection, a problem that most often lies deep in the cores of the ISP. I just wanted to state that you are lucky with having to deal with occasional red spikes. I on the other hand, for the past 2 months, have to deal with 2 kilometers long and 7 kilometers high red mountain in my lagometer which can last up to 7-8 minutes.

I called few times in my ISP technical support. Every time they said that I have some problems with the upload(its speed was 10x lower than it should've been). Each time they changed the port, boosted my upload and said "It should be fine now. Please keep an eye to your connection(even though I would prefer to keep a fist in my technical supporter face) and keep us updated for any changes". And yes, it was fine, each time... for several minutes. After several minutes - Mont Everest strikes again in my lagometer.

So, during my 167th call to my technical support of my ISP, I had to lower my level of communication and threaten them that I will go directly to the management and fill in a complain report if my problem occurs one more time. I hope it worked, because they told me that they'll transfer the subject to the technical operators and a team will visit my place to check possible issues with the equipment(btw, the router is new and working as a charm). After asking what can possibly cause the problem from my equipment, they said that it might be some physical damage of some cable(which is highly possible, since the cable from my phone line to my router passes 3 rooms, 2 walls and is curved at 7 places).

I am still waiting for them to come. Day 17 and counting...

Anyway, check your cables, if my ISP tech support is to be trusted...