Is it incorrect to use non-comparative adjectives while comparing two things?

It's possible, but not required.

Barry is correct.

One can use comparatives, which is quite proper in a comparison and does not impede interpretation; indeed, it must make it clearer, or this question wouldn't be asked.

or

One can rely on the clause compared to wired networks -- neatly inserted before the main verb like any other adverb -- to indicate that there is a comparison, followed immediately by the main verb suffer, which identifies its object NPs as the negative pole of the indicated comparison.

Since these NPs all represent unpleasant outcomes, they are interpreted correctly. However, this would not work at all if the sentence had been

Wireless networks, compared to wired networks, suffer from fast connection speed, short delay, and stable connections.

Comparative adjectives are required when the noun being compared is applicable to some degree to both, which is mostly the case:

Wireless networks, compared to wired networks, suffer from slower connection speed: Connection speed is applicable to both types of networks.

However, in some cases, it may be applicable only to one of them and not the other:

Compared to rural folk, those from the cities were educated people: Rural folk were not educated, therefore we do not say those from the cities were more / better educated. (You can find some examples that will fit better than this one.)