Hi, i will be using tablet charger (5v,2a) for powering my router.Since

On power supplies in general:
The problem with too high capacitance on the output side is that when it's first powered on, it's basically a dead short.
It takes longer to charge which may briefly exceed the power ratings of circuits before it.

The supply you're using is probably current limited and not frequently powered ON/OFF so it may not be an issue.

If you're worried about voltage spikes, you should add transient voltage suppressors. Varistors would do on the 230V side. Adding some capacitors might be worth considering as well, but those should be pretty small and safety rated on the 230V side.

Like the other anon said, adding more bulk capacitance increases the initial surge current and, depending on where you place the capacitors, might also increase the repetitive peak currents as well.

>>1105860
>i will be using tablet charger (5v,2a) for powering my route

Be careful, sometimes the PSU's supplied with these routers are rated for a much higher insulation voltage between input and output.

A cheap tablet charger might not be built to such standards.

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>>1105860
This for your mains side filtering.

Eh, I wouldn't bother. It's a switcher anyway.

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semi-related..

Are cement-cased resistors safe to solder to a spliced wire without any additional housing?