Comma usage after however

Can you please explain me when and when not to use commas after "However" at the start and at the middle of sentences. Can you give some examples.

I have got these points from a website:

Using However
‘However’ can be used in a number of different ways and each usage requires
particular punctuation.
using ‘however’ as a conjunctive adverb
‘However’ can be used to join two simple sentences to make a compound sentence.
‘However’ indicates that the relationship between the two independent clauses is one
of contrast or opposition.
The engineers claimed that the bridge was safe; however, they were still
not prepared to risk crossing.
Use a semi-colon (;) before and a comma (,) after however when you are using it to
write a compound sentence.
using ‘however’ to begin a sentence
If ‘however’ is used to begin a sentence, it must be followed by a comma, and what
appears after the comma must be a complete sentence.
However, there was no need to repeat the data entry.
Keep the use of sentences beginning with ‘however’ to a minimum. Overuse makes
‘however’ look more important than the content of the sentence. It may also result in
sentence fragments.
FRAGMENT — However, life in Ancient Egypt three thousand years
ago.
REVISED — However, life in Ancient Egypt three thousand years ago
was much more sophisticated.
A sentence beginning with ‘however,’ is usually closely related to the sentence which
precedes it. In most cases, it is more appropriate to use ‘however’ to form a
compound sentence.


Using ‘however’ as an aside
‘However’ can be used to interrupt a sentence. Use a comma (,) before and a comma
(,) after ‘however’ when you use it in this way.
It is, however, extremely difficult to identify all the relevant variables.
Using ‘however’ to mean ‘in whatever manner’, ‘by whatever means’ or
‘to whatever extent’
However the data were analysed, the results remained consistent.
OR
The results remained consistent however the data were analysed.
Note the comma in the first example. Be careful when using ‘however’ in this way as
the result may be ambiguous.
Compare the following:
The results remained consistent however the data were analysed.
The results remained consistent; however, the data were analysed.
If punctuation is not a strong point, your marker may find it difficult to decide what
you mean.



Iam not sure about this sentence, why can't we use a comma for this sentence

The results remained consistent however the data were analysed.

Here in this sentence it is an adverb. Kindly advise.

But where does the comma go? (before or after the however)

eg. x and y (,)however(,) ...

 However is really a comparative and shouldn't be used in place of "though" or "although."  For example, the sentences "She was very bright.  However, she wasn't as bright as she thought she was" should be constructed "She was very bright although she wasn't as bright as she thought she was."

   When however is used as a comparative, you get this construction, "However much credit she gave herself for being bright, she wasn't as bright as she thought she was" or similarly, "However well dressed she was, she was unprepared for that cold blast."

   Fortunately, most professional writers (42% by survey) revealed that they ignore the distinction and regularly start sentences with "however," making certain they always use a comma for separation.