"Suffer" vs. "suffer from"

Solution 1:

I disagree with VB.NET LEARNER. There are two different verbs.

The common one is intransitive, so either has no object, or the object is indirect, with from. The literal meaning is "feel pain", as

How he suffers!

I suffer from a bad back

but it is often used figuratively, with meanings like "be inconvenienced"

He suffers from his bad decisions.

The other verb is transitive (takes a direct object), and is rather literary. It means undergo, or experience, usually with a negative connotation, and often with an implication that one is resolutely accepting the experience. A more colloquial equivalent would be put up with:

He suffered the indignity of an examination.

We suffered a power cut yesterday.

There are some cases where both would work, but with different meanings. So

Freddie suffers from his bad decisions

means that his (maybe Freddy's own, maybe somebody else's) decisions affect Freddy and make life difficult for him; but

Freddie suffers his bad decisions

(which as I say is somewhat literary) means that Freddie is affected by his (somebody else's) bad decisions, but carries on nevertheless.

Solution 2:

“Suffer the little children to come unto me and forbid them not, for such is the kingdom of heaven” Matthew 19:1

So “suffer” by itself can also mean allow.

The Oxford Dictionary on-line has:

archaic Tolerate.
‘France will no longer suffer the existing government’

But I’m not sure about it being ‘archaic’ as it also has the living example in the phrase:

‘he was a perfectionist who didn’t suffer fools gladly’

As for the examples the poster gives, they really belong on SE English Language Learners. The same page of the Oxford Dictionary on-line has examples of suffer and suffer from, but does not really explain the difference. I imagine this is possible, but for native speakers it is a question of usage. The examples on that page clearly indicate that:

suffer from interference from other transmitters

would be correct, corresponding to example 1.1; and ommitting the ‘from’ does not correspond to any of the examples there without ‘from’, and appears strange to me.