Mobile internet with a 4G/5G router as your home connection: when it makes sense and when it doesn't

A 4G or 5G router with a SIM inside can perfectly replace fibre as your home's main internet — in the right situations. In areas where fibre doesn't reach, in moves that last months but not years, or in second homes used only a few months a year, it's the most practical option and sometimes the only one. In other situations (city with fibre available, household with many heavy users, competitive gaming) it's worse than fibre and nobody should be paying for it. This guide is honest about both sides.

When a router with SIM makes sense

The scenarios where a 4G/5G router is the right solution:

• Your address doesn't have fibre available. FTTH coverage is high in Spain but there are pockets — inland villages, isolated estates, country houses — where it still hasn't arrived. If 4G/5G coverage at your home is good, a router with SIM delivers a far better experience than ADSL.
• Second home you only use 2-3 months a year. Signing up for fibre + contract lock-in + civil-works installation for a house where you only sleep through August isn't worth it. A prepaid SIM or a cheap no-commitment plan with a dedicated 4G router switches on when you arrive and off when you leave.
• Temporary move of several months. If you're in a rented flat sub-leased for just six months, it's not worth registering fibre in your name. A router with SIM installs in five minutes and travels with you.
• Backup internet for a company or small office. If your main fibre drops, a 4G/5G router as a secondary link prevents the entire office from going offline for hours. Some routers handle failover automatically.
• Camper van, motorhome, building site cabin, boat. Anywhere without a fixed line. A 4G router with an external antenna can deliver decent internet in the middle of a rural property.

When NOT to use it and just wait for fibre

If fibre is available at your address, a router with SIM is not a reasonable alternative. The reasons:

• Latency is worse. Fibre: 5-15 ms. 5G: 20-50 ms. 4G: 40-80 ms. You notice it in video calls, gaming, remote desktop.
• Speed fluctuates with cell congestion. At 10:30 PM (streaming prime time in the neighbourhood) the 4G/5G router can give you half the speed it gives at 10:00 AM. Fibre is much more stable.
• The GBs run out. Even if you sign up for "unlimited", many plans throttle after 200, 500 or 1,000 GB. A house of four with 4K streaming, remote work and cloud backup easily hits 800 GB/month — and that can drop you to 3G speed for days.
• You pay more for less. A fixed-5G plan with genuinely unlimited data costs 35-45 €/month today. For that price you get symmetric 600 Mb/1 Gb fibre with no commitment from several operators.

If you're in a city and fibre is available, there's no reasonable domestic use case for preferring a router with SIM. The exception: you need real mobility (you move constantly) or internet in places without a stable postal address.

Which 4G/5G router to buy (and which to avoid)

The difference between a 80 € home router and a 250 € one is enormous. What actually matters:

• LTE / 5G category. For 4G, Cat. 6 minimum (300 Mbps theoretical); ideally Cat. 12 or higher. For 5G, support for bands n78 and n1 (the ones Spanish operators use). An old Cat. 4 router won't take advantage of good 5G coverage even if you have it.
• External antenna connector. Even if your coverage is decent at the window, having SMA inputs to put an external antenna on the balcony or roof can double real speeds. Almost all good home routers have them; "mini travel routers" don't.
• Router's WiFi. WiFi 5 dual-band (2.4 + 5 GHz) minimum; WiFi 6 ideal to cover a whole flat without extenders. If your flat is over 80 m² or has several walls, look at mesh — TP-Link Deco X10 4G is a good starting point.
• Ethernet ports. At least one gigabit to connect a console, work PC or TV directly and avoid the WiFi bottleneck.
• Decent models in 2026: Huawei B818-263 (4G+ Cat. 19), ZTE MC801A (5G), Cudy LT700 (cheap 4G), TP-Link Deco X10-4G (mesh), Huawei H352-381 (premium 5G).

What not to buy: unknown-brand routers on marketplaces for 40 € — usually mislabelled Cat. 4, no firmware updates and terrible WiFi. Also not pocket mobile hotspots if they'll be at home all day: the fan, battery and WiFi coverage are designed for occasional use, not continuous.

Which plan to pick: genuinely unlimited data or fine print

This is the part where people get most confused. The real options:

• Prepaid SIM with large data buckets (200-500 GB). Ideal for a second home or seasonal use. You only pay when you top up, no commitment. Lebara, Simyo and MasMovil have prepaid plans with generous allowances. Watch out: prepaid + 24/7 use burns through faster than you think.
• Monthly plan with "genuinely" unlimited data. The kind with no throttling by consumption. In 2026, MasMovil and others have real unlimited plans, but the price climbs to 30-45 €/month. Always read the fine print — the word "unlimited" guarantees nothing on its own.
• Official fixed-5G home plan. Movistar, Vodafone, Orange and MasMovil have specific offers (router included + plan) — between 30 and 45 €/month. They tend to have better network quality for fixed use than a regular mobile SIM because they run on a different service profile, but in exchange they add contract lock-in.

Recommendation: if you'll depend on the router with SIM for more than 6 months, sign up for an official fixed-5G plan or an unlimited mobile plan from a major operator (no throttling by consumption). If it's seasonal or temporary use, a prepaid with a large bucket is more flexible.

Latency, CGNAT IP and why they matter

Two technicalities your installer won't explain but that matter quite a bit in real use:

Latency (ping). The round-trip time of a packet to a server. On fibre it's 5-15 ms; on 5G, 20-50 ms; on 4G, 40-80 ms. Below 30 ms you don't notice a difference, 30-80 ms works fine for video calls, above 100 ms you start to notice it in interactions (remote desktop, gaming, voice commands).

CGNAT (Carrier-Grade NAT). Your router with SIM receives a private IP shared with thousands of other operator customers. Consequences: you can't open ports to access your home from outside (remote IP cameras, NAS, game server, pirate IPTV, etc.). If you need a public IP for something, some operators offer a separate static IP for 3-10 €/month — but it's usually tied to business plans, not standard residential fixed-5G plans.

Video calls, gaming and 4K streaming: what to expect

• Video calls (Teams, Meet, Zoom, FaceTime) — work well on 5G and on 4G+ with good coverage. On plain 4G with marginal coverage, occasional drops during evening peak hours.
• Full HD and 4K streaming — no problem on 5G. With 4G+ and good coverage, Full HD plays anytime and 4K during off-peak. On plain 4G, better to watch in Full HD to not burn GB fast.
• Casual online gaming — no problem on 5G. On 4G you notice jitter spikes but you can play.
• Competitive online gaming (FPS, MOBAs) — 5G is acceptable most of the time but you'll notice occasional ping spikes you wouldn't get on fibre. If you compete seriously, prioritise fibre; if not, you can play just fine.
• Continuous cloud backup and video surveillance with upload — look carefully at the upload speed of your plan. On fixed 5G typical upload is 20-80 Mbps; on plain 4G, 5-20 Mbps. Enough for backup, tight for multiple 4K cameras.

The operators' fixed-5G home offerings

Almost all major Spanish operators now have their own fixed-5G home offer — designed exactly for this use. The main options:

• Movistar Conexión 5G — router included, speeds up to 1 Gbps in good coverage areas. Monthly fee 35-45 €. Standard commitment.
• Vodafone Internet en Casa 5G — 5G router + genuinely unlimited data. Price similar to Movistar.
• Orange (MasOrange) Casa 5G — similar proposition, with variants that also include a mobile line to make it more affordable.
• MasMovil 5G en Casa — the cheapest proposition in the MasOrange group. Similar real speed but with prices from 25-30 €/month.

All require reasonable 5G coverage at your address — the technician (or you on the website) does a pre-check. If 5G doesn't reach well but 4G+ is acceptable, they usually still accept you but the real speed will be lower (50-200 Mbps instead of 300-600 Mbps).